can't get past initial black screen

You can't mount sda, its a drive, you can only mount partitions

Try reinstalling GRUB to the Master Boot Record:
https://help.ubuntu.com/community/Grub2#Reinstalling%20GRUB%202

Right-O
tried that, got as far as
"sudo mount /dev/sda1 /mnt" and pressed RETURN. Nothing happened after that. Should I wait for the "ubuntu@ubuntu:~$" prompt or just go straight ahead and type the next line?

There's no text at all produced after you enter "sudo mount /dev/sda1/mnt" and press RETURN?

Please select all the text from the Terminal (Edit > Select All), copy it to the clipboard (Edit > Copy), and paste it here, so I can see more fully what's going on.

To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.

ubuntu@ubuntu:~$ sudo fdisk -l

Disk /dev/sda: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000ee3a2

   Device Boot Start End Blocks Id System
/dev/sda1 * 1 19275 154821632 83 Linux
/dev/sda2 19275 19458 1466369 5 Extended
/dev/sda5 19275 19458 1466368 82 Linux swap / Solaris
ubuntu@ubuntu:~$ sudo mount /dev/sda1 /mnt

It's been sitting there for almost an hour now. I have a flashing cursor beneath the bottom row, but that's all. I'm confused (easily done!)

Press Ctrl+C, which cancels the operation. Then run:

mount

And paste the output there. That may help in figuring out what's going on.

Thank you for your help so far :-)
Here's what I get...

ubuntu@ubuntu:~$ mount
aufs on / type aufs (rw)
none on /proc type proc (rw,noexec,nosuid,nodev)
none on /sys type sysfs (rw,noexec,nosuid,nodev)
fusectl on /sys/fs/fuse/connections type fusectl (rw)
none on /dev type devtmpfs (rw,mode=0755)
none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
/dev/sr0 on /cdrom type iso9660 (ro,noatime)
/dev/loop0 on /rofs type squashfs (ro,noatime)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
none on /dev/shm type tmpfs (rw,nosuid,nodev)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev)
none on /var/run type tmpfs (rw,nosuid,mode=0755)
none on /var/lock type tmpfs (rw,noexec,nosuid,nodev)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev)
gvfs-fuse-daemon on /home/ubuntu/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=ubuntu)
ubuntu@ubuntu:~$

Everything looks to be in order... When you try to run the command again "sudo mount /dev/sda1 /mnt" does it work?

Hi, I am away from the office until Monday -I'll try it as soon as I
get back. Cheers

On 5 Mar 2011, at 07:32, Eliah Kagan <<email address hidden>
 > wrote:

> Your question #147704 on grub2 in ubuntu changed:
> https://answers.launchpad.net/ubuntu/+source/grub2/+question/147704
>
> Eliah Kagan requested for more information:
> Everything looks to be in order... When you try to run the command
> again
> "sudo mount /dev/sda1 /mnt" does it work?
>
> --
> To answer this request for more information, you can either reply to
> this email or enter your reply at the following page:
> https://answers.launchpad.net/ubuntu/+source/grub2/+question/147704
>
> You received this question notification because you are a direct
> subscriber of the question.

OK I'm back!
I've just tried sudo mount /dev/sda1 /mnt
same result as before i.e. after pressing RETURN I get a flashing cursor but nothing else

Could you run:
   sudo fsck /dev/sda1
It will check consistency of file system (partition need to be not mounted!).

Yep: this is what I get...

ubuntu@ubuntu:~$ sudo fsck /dev/sda1
fsck from util-linux-ng 2.17.2
e2fsck 1.41.12 (17-May-2010)
fsck.ext4: Device or resource busy while trying to open /dev/sda1
Filesystem mounted or opened exclusively by another program?
ubuntu@ubuntu:~$

Could you run:
  mount | fgrep sda1

Could you have a look at: /var/log/boot.msg

OK, nothing noticeable happened. Is that right?

Sorry: your last message came-up as I was typing.
That tells me... No such file or directory

The data I got from forum was wrong. Could you run:
    sudo fgrep sdb1 /var/log/* | fgrep -v readahead
This time I checked on my PC.
Could you also run:
   ls -l /dev/sda1
Currently, I have any idea of origin of problem.

OK, here are the results...

ubuntu@ubuntu:~$ sudo fgrep sdb1 /var/log/* | fgrep -v readahead
/var/log/auth.log:Mar 14 22:12:32 ubuntu sudo: ubuntu : TTY=pts/0 ; PWD=/home/ubuntu ; USER=root ; COMMAND=/bin/fgrep sdb1 /var/log/alternatives.log /var/log/apparmor /var/log/apt /var/log/auth.log /var/log/boot /var/log/boot.log /var/log/bootstrap.log /var/log/btmp /var/log/casper.log /var/log/ConsoleKit /var/log/cups /var/log/daemon.log /var/log/debug /var/log/dist-upgrade /var/log/dmesg /var/log/dmesg.0 /var/log/dpkg.log /var/log/faillog /var/log/fontconfig.log /var/log/fsck /var/log/gdm /var/log/installer /var/log/jockey.log /var/log/kern.log /var/log/lastlog /var/log/lpr.log /var/log/mail.err /var/log/mail.info /var/log/mail.log /var/log/mail.warn /var/log/messages /var/log/news /var/log/pm-powersave.log /var/log/pycentral.log /var/log/samba /var/log/speech-dispatcher /var/log/syslog /var/log/udev /var/log/ufw.log /var/log/unattended-upgrades /var/log/user.log /var/log/wtmp /var/log/Xorg.0.log /var/log/Xorg.0.log.old
/var/log/kern.log:Mar 14 22:11:43 ubuntu kernel: [ 584.811674] sdb: sdb1
/var/log/messages:Mar 14 22:11:43 ubuntu kernel: [ 584.811674] sdb: sdb1
/var/log/syslog:Mar 14 22:11:43 ubuntu kernel: [ 584.811674] sdb: sdb1
ubuntu@ubuntu:~$ ls -l /dev/sda1
brw-rw---- 1 root disk 8, 1 2011-03-14 22:02 /dev/sda1
ubuntu@ubuntu:~$

Sorry, I did the test on sdb1 as sda1 on my computer is a Windows partition.
Could you run: sudo fgrep sda1 /var/log/* | fgrep -v readahead

ubuntu@ubuntu:~$ sudo fgrep sda1 /var/log/* | fgrep -v readahead
/var/log/auth.log:Mar 15 19:38:14 ubuntu sudo: ubuntu : TTY=pts/0 ; PWD=/home/ubuntu ; USER=root ; COMMAND=/bin/fgrep sda1 /var/log/alternatives.log /var/log/apparmor /var/log/apt /var/log/auth.log /var/log/boot /var/log/boot.log /var/log/bootstrap.log /var/log/btmp /var/log/casper.log /var/log/ConsoleKit /var/log/cups /var/log/daemon.log /var/log/debug /var/log/dist-upgrade /var/log/dmesg /var/log/dmesg.0 /var/log/dpkg.log /var/log/faillog /var/log/fontconfig.log /var/log/fsck /var/log/gdm /var/log/installer /var/log/jockey.log /var/log/kern.log /var/log/lastlog /var/log/lpr.log /var/log/mail.err /var/log/mail.info /var/log/mail.log /var/log/mail.warn /var/log/messages /var/log/news /var/log/pm-powersave.log /var/log/pycentral.log /var/log/samba /var/log/speech-dispatcher /var/log/syslog /var/log/udev /var/log/ufw.log /var/log/unattended-upgrades /var/log/user.log /var/log/wtmp /var/log/Xorg.0.log /var/log/Xorg.0.log.old
/var/log/dmesg:[ 3.686349] sda1 sda2 < sda5 >
/var/log/dmesg:[ 7.195614] EXT4-fs (sda1): INFO: recovery required on readonly filesystem
/var/log/dmesg:[ 7.195621] EXT4-fs (sda1): write access will be enabled during recovery
/var/log/dmesg:[ 7.259688] EXT4-fs warning (device sda1): ext4_clear_journal_err: Filesystem error recorded from previous mount: IO failure
/var/log/dmesg:[ 7.259694] EXT4-fs warning (device sda1): ext4_clear_journal_err: Marking fs in need of filesystem check.
/var/log/kern.log:Mar 15 18:17:56 ubuntu kernel: [ 3.686349] sda1 sda2 < sda5 >
/var/log/kern.log:Mar 15 18:17:56 ubuntu kernel: [ 7.195614] EXT4-fs (sda1): INFO: recovery required on readonly filesystem
/var/log/kern.log:Mar 15 18:17:56 ubuntu kernel: [ 7.195621] EXT4-fs (sda1): write access will be enabled during recovery
/var/log/kern.log:Mar 15 18:17:56 ubuntu kernel: [ 7.259688] EXT4-fs warning (device sda1): ext4_clear_journal_err: Filesystem error recorded from previous mount: IO failure
/var/log/kern.log:Mar 15 18:17:56 ubuntu kernel: [ 7.259694] EXT4-fs warning (device sda1): ext4_clear_journal_err: Marking fs in need of filesystem check.
/var/log/messages:Mar 15 18:17:56 ubuntu kernel: [ 3.686349] sda1 sda2 < sda5 >
/var/log/messages:Mar 15 18:17:56 ubuntu kernel: [ 7.195614] EXT4-fs (sda1): INFO: recovery required on readonly filesystem
/var/log/messages:Mar 15 18:17:56 ubuntu kernel: [ 7.195621] EXT4-fs (sda1): write access will be enabled during recovery
/var/log/messages:Mar 15 18:17:56 ubuntu kernel: [ 7.259688] EXT4-fs warning (device sda1): ext4_clear_journal_err: Filesystem error recorded from previous mount: IO failure
/var/log/messages:Mar 15 18:17:56 ubuntu kernel: [ 7.259694] EXT4-fs warning (device sda1): ext4_clear_journal_err: Marking fs in need of filesystem check.
/var/log/syslog:Mar 15 18:17:56 ubuntu kernel: [ 3.686349] sda1 sda2 < sda5 >
/var/log/syslog:Mar 15 18:17:56 ubuntu kernel: [ 7.195614] EXT4-fs (sda1): INFO: recovery required on readonly filesystem
/var/log/syslog:Mar 15 18:17:56 ubuntu kernel: [ 7.195621] EXT4-fs (sda1): write access will be enabled during recovery
/var/log/syslog:Mar 15 18:17:56 ubuntu kernel: [ 7.259688] EXT4-fs warning (device sda1): ext4_clear_journal_err: Filesystem error recorded from previous mount: IO failure
/var/log/syslog:Mar 15 18:17:56 ubuntu kernel: [ 7.259694] EXT4-fs warning (device sda1): ext4_clear_journal_err: Marking fs in need of filesystem check.
/var/log/udev:KERNEL[1300213077.508509] add /devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda1 (block)
/var/log/udev:DEVPATH=/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda1
/var/log/udev:DEVNAME=sda1
/var/log/udev:UDEV [1300213083.973133] add /devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda1 (block)
/var/log/udev:DEVPATH=/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda1
/var/log/udev:DEVNAME=/dev/sda1
ubuntu@ubuntu:~$

The file system of sda1 is corrupted: "ext4_clear_journal_err: File system error recorded from previous mount: IO failure". We need to do a fsck, which is what we fail to do!

Sounds serious! Is my computer beyond help? The hard disc isn't very old - certainly less than a year. Or is it some other component failing to communicate with the HD?

It's too technical for me. In file system, there is a flag to tell that file system is mounted or used for hibernation. Perhaps it's the issue.
Could convert this question into a bug and request help from ubuntuforums.org, to reach more people.
Could you try
   tune2fs -fl /dev/sda1 # tool to modify internals of file system
and
   e2fsck /dev/sda1 # direct call to file system checker
from Live CD, and see if you can access partition.

gives me this...

ubuntu@ubuntu:~$ tune2fs -fl /dev/sda1 # tool
tune2fs 1.41.12 (17-May-2010)
tune2fs: Permission denied while trying to open /dev/sda1
Couldn't find valid filesystem superblock.
ubuntu@ubuntu:~$ e2fsck /dev/sda1 # direct call
e2fsck 1.41.12 (17-May-2010)
e2fsck: Permission denied while trying to open /dev/sda1
You must have r/w access to the filesystem or be root
ubuntu@ubuntu:~$ sudo e2fsck /dev/sda1 # direct call
e2fsck 1.41.12 (17-May-2010)
e2fsck: Device or resource busy while trying to open /dev/sda1
Filesystem mounted or opened exclusively by another program?
ubuntu@ubuntu:~$

It looks bad. Could you install "testdisk" and run it to see if it is able to access disk.
Do you have data to recover ? Do you have an external media bigger than sda1 ?

Hi
tried to install Testdisk but it never gets past about 95%.
Most of my data are backed-up onto a 1TB external hard drive so the answer to that is YES. Does it look like I'm going to have to re-install? If so, is this likely to happen again?

If all data are backed-up, reinstalling is the easiest way. You will need to reformat partition. If it will happen again, I don't know. Probably if cause is hardware. Perhaps not if it was a rare software issue. In all cases, backup frequently in the following weeks. Listen carefully to disk. If disk plate lost its geometry, it should make more noise. If it is electronic, no warning.
You could use SMART facilities to check disk health. You can do this from System->Administration->Disk Utilities.

Hmmm...
running SMART data gives me a warning in Reallocated Sector Count: Normalized 59; Worst 59; Threshold 10; Value 389 sectors.
Does this mean my hard drive is kaput (it's was installed about 6 months ago)?

I'm not an expert in hardware, but it's too much. I presume either you have an issue in SATA wire/SATA controller or else on hard disk. Perhaps you bought a defective disk. If you value your data, buying a now disk should be safer.

Just to tidy things up: never solved the problem and that laptop has been "filed under b1n"
Thanks for your valiant attempts anyway! :-)