how can I view file on my window vista c drive?

First, if you haven't already, see if the C: partition is in the Places menu (at the top of the screen). It will not be called "C:" -- instead, it will be referred to by its volume label, or by an indication of its size. If there are any entries in the Places menu that you don't recognize, check them out to see if they are your C: partition.

If that fails, then open up a Terminal window (Applications > Accessories > Terminal) and run these two commands (type them in or paste them, separately, pressing enter after each):

mount
sudo fdisk -l

In the second command, the "-l" is lower case "-L". That command might prompt you for your password; if so, it's OK to enter it. As you are entering your password, you won't see any placeholder characters (like *). But if you enter your password correctly and press enter, the command will work.

Then copy all the text in the Terminal to the clipboard and paste it here. This will provide useful diagnostic information for figuring out why you are unable to see that partition that is called C: in Windows.

Thanks a lot for your answer. I still cannot find c: partition nor /host drive. The following is what shows after the command sudo fdisk -l:

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 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: 0x651106ff

   Device Boot Start End Blocks Id System
/dev/sda1 1 1274 10233373+ 27 Unknown
/dev/sda2 * 1275 31055 239210496 6 FAT16
/dev/sda3 31055 60802 238941184 7 HPFS/NTFS

Disk /dev/sdb: 2000 MB, 2000748032 bytes
64 heads, 63 sectors/track, 969 cylinders
Units = cylinders of 4032 * 512 = 2064384 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xd757d757

   Device Boot Start End Blocks Id System
/dev/sdb1 1 969 1953439+ 6 FAT16

I have only one 500 gb physical harddrive plus one 2 gb usb flash drive attached.
Your help is greatly appreciated.

that doesn't look right - /dev/sda2 shouldn't be FAT16.

Can you also give the output of:
sudo blkid

and

mount

and (the next one is lower case LS)

ls /host

Thanks

@bcbc: Manufacturer-installed system repair utilities often reside inside a small FAT16 partition at the beginning of the drive on which Windows is installed. That's probably what this is, and it's probably no cause for alarm.

@Eric: You should still go ahead and run those three commands.

@Eliah, yes but it has the boot flag set and vista can't boot off fat16.
Plus it looks like it's 240GB. So this is likely an error.

@bcbc: Manufacturer-installed system repair utilities installed in FAT16 partitions are bootable and not based on Windows Vista. However, you're certainly right about the huge size...that is cause for some alarm!

@Eliah, the boot flag is used to show the simple windows bootloader where the windows install is located. There can be many bootable partitions, but only one with the boot flag (normally). Recovery partitions usually require a hook in the (custom) MBR bootloader or via the windows bootmanager to boot.

I've seen a number of cases where fdisk and blkid don't agree on the file system. I don't know what causes this, but it happens. Usually testdisk can fix it. I'm also not sure what effect this has on Windows - I guess if windows wasn't booting we'd have heard about it.

Anyway... let's see what those commands say.

@bcbc: My understanding is that some recovery programs (or their own dedicated boot loaders) boot first, and then transfer control to Windows. When Windows cannot boot, the recovery program takes over. Therefore, it could be flagged as the partition from which the Windows installation boots.

...But you're right, let's see what the commands say. (Plus, as you pointed out, that FAT16 partition is rather large; my hypothesis does not explain that.)

Hi guys:
Base on your guidance, I finally find my documents on Windows' C: drive. I opened the home folder: underneath it I saw directory name "File System": open it was the "host" directory hiding place. I am now able to see all my files there. Although I still have no idea what you guys were talking about, I am happy to find what I was looking for.
Thanks a million for your help.

Thanks bcbc, that solved my question.

Oh, I am sorry, but here are the output Mr. bcbc requested:
eric@ubuntu:~$ sudo blkid
[sudo] password for eric:
/dev/loop0: UUID="b8dc21a9-db61-4d65-8dc5-4e63254ec683" TYPE="ext4"
/dev/sda1: LABEL="PQSERVICE" UUID="BE002106E49BED2A" TYPE="ntfs"
/dev/sda2: LABEL="ACER" UUID="5CA8BE0AA8BDE326" TYPE="ntfs"
/dev/sda3: LABEL="DATA" UUID="C46C01016C00EFCA" TYPE="ntfs"
/dev/sdb1: SEC_TYPE="msdos" UUID="5CF1-E387" TYPE="vfat"

eric@ubuntu:~$ mount
/dev/loop0 on / type ext4 (rw,errors=remount-ro)
proc on /proc type proc (rw,noexec,nosuid,nodev)
none on /sys type sysfs (rw,noexec,nosuid,nodev)
none on /sys/fs/fuse/connections type fusectl (rw)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
none on /dev type devtmpfs (rw,mode=0755)
none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
none on /dev/shm 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)
none on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
/dev/sda2 on /host type fuseblk (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other,blksize=4096)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev)
gvfs-fuse-daemon on /home/eric/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=eric)
/dev/sdb1 on /media/5CF1-E387 type vfat (rw,nosuid,nodev,uhelper=udisks,uid=1000,gid=1000,shortname=mixed,dmask=0077,utf8=1,flush)
/dev/sda3 on /media/DATA type fuseblk (rw,nosuid,nodev,allow_other,blksize=4096,default_permissions)

eric@ubuntu:~$ ls /host
16f76331050045d0a98f15f3dc449f HiTRUSTDrive Program Files
-20070716.log inetpub PSD.log
Acer Intel $RECYCLE.BIN
ATI IO.SYS RHDSetup.log
autoexec.bat MDisc.log SDMA.log
Boot MDR.log setup.log
bootmgr MSDOS.SYS Sys_LogWin.log
BOOTSECT.BAK MSOCache System Volume Information
CLMS.log pagefile.sys ubuntu
config.sys PerfLogs Users
CopyDVD PMovie.log Windows
Documents and Settings PnR.log wubildr
DRV ProgramData wubildr.mbr

@Eric, glad to hear your problem is solved.

There is a difference in the partition type (FAT16) for /dev/sda2 and the file system (NTFS). This doesn't seem to have any adverse affect since you are able to boot Windows and Ubuntu without any issues. It also seems fairly common - so I would probably just leave it alone.