My Ubuntu OS now no longer finds ANY USB devices.

Unplug every USB device and enter a terminal.
Go to /media folder by typing "cd /media".
See its content with "ls -a".
There should be a folder for your cdrom and other devices.
This folder is where automounted devices are shown.

As your PC crashed operating your external HDD, there should be a folder for that HDD even when it is not plugged in. This prevents the mounting of the HDD drive when plugged again.

Remove that folder by typing "sudo rm deviceName" where deviceName is the name Ubuntu gave to your HDD.
Also remove lock files in media folder. Their name starts with a dot.

If you have a doubt, please respond with the output of "ls -a" in that folder so we can guide you.

The output from Ls -a in /media is as follows:

. .. cdrom cdrom0 cdrom1 floppy floppy0 .hal-mtab

There doesnt appear to be any icon for the external drive. There was one when it stopped working and i unmounted it and deleted it from the desktop.

Nothing plugged into USB works Camera; Telephone; Mouse; Scanner or usbto IDE controller. Nothing.

Put a HDD with Win98 on it into the boot sequence and boot into WinDoze98 and Lo and Behold - The USB devices work. so the implication is that something in Ubuntu is broken.

Just tried the mount command with no switches and got the following:

richard@UbuntuPC:/media$ mount
/dev/sda1 on / type ext3 (rw,relatime,errors=remount-ro)
proc on /proc type proc (rw,noexec,nosuid,nodev)
/sys on /sys type sysfs (rw,noexec,nosuid,nodev)
varrun on /var/run type tmpfs (rw,noexec,nosuid,nodev,mode=0755)
varlock on /var/lock type tmpfs (rw,noexec,nosuid,nodev,mode=1777)
udev on /dev type tmpfs (rw,mode=0755)
devshm on /dev/shm type tmpfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
lrm on /lib/modules/2.6.24-19-generic/volatile type tmpfs (rw)
securityfs on /sys/kernel/security type securityfs (rw)
gvfs-fuse-daemon on /home/richard/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=richard)

Delete file .hal-mtab, it is what is blocking you. It should have been deleted when HDD was removed, but it wasn't as PC crashed.

tried that - the file is locked and i do not have permission to delete it.

tried user password and admin password (same in Ubuntu) and file will not go...

Please, copy message given when you type "sudo rm .hal-mtab" in that folder.

finally managed to delete it but the USB devices are not being recognised.

So will try a reboot to see if that helps.

update to my woes.

Managed to delete .hal-mtab-lock after a few attempts of typo errors. It helps to type the command properly. rebooted the machine and it would not start with the external HDD plugged in. unplug the usb cable and the PC will run.

To clarify, the pc will POST and pass control to the OS (ubuntu8.04) and this will have the black screen with the orange bar moving side to side. about 10 minutes later it STILL has the orange bar moving from side to side. Unplug the external USB HDD and it leaps into the login screen. However none of the other USB peripherals (Scanner Bluetooth IPOD-dock etc) are recognised either. Plug the drive and nothing happens.

on an upside, a brand new 8gb usb dongle was plugged in today and that worked, for about 5 minutes. I unplugged it and plugged it into another usb port and now that too does not mount. either in the original port or any other.

I am suspecting that a complete reinstall is coming my way.....

One reinstall later and everything is working as it should (for now).

All my USB peripherals are working as they should and my external HDD appears on the desktop at boot, so I am now happy.

It would appear that something ¨Got Broke¨ during an update or during an install. If this happens again then I will be looking at what I have installed recently and see if that was the culprit rather than do a full install. It took hours to re-download the programs I wanted. And, is it possible to copy the files from the repositories to a local source IE a DVD on my PC so I dont have to keep a live internet access going?

Thanks to all those who offered advice...