I upgraded from 10.04 to 12.04LTS. Upgrade went fine, even restarted couple of times. Then the next day while booting into Ubuntu, after the grub, it gave the error Kernel panic : not syncing vfs unable to mount root fs on unknown block (0,0). I then booted into live CD and tried the following commands, based on other posts on this forum:

sudo fdisk -l
As the 8 was on /dev/sda1, 
sudo mount /dev/sda1 /mnt
sudo mount --bind /dev /mnt/dev
Now I got the message:
mount: mount point /mnt/dev does not exist

Then tried

sudo mount --bind /proc /mnt/proc
Again got the message:
mount point point /mnt/proc does not exist.
then tried
sudo chroot /mnt
Got message:
chroot: failed to run comman '/bin/bash': No such file or directory

Now have no clue what to do next. Unable to boot into Ubuntu. Please help.

Jitesh