disk drive for / is not ready yet or not present
 

I have upgraded my OS to version 12.04. after completion of upgrade the laptop get restarted. But the root is not mounting. It shows a message
The disk drive for / is not ready yet or not present

What is the solution for this problem?

Or atleast can i restore my lap to the previous version?

Previous Version...
 

Not the answer your looking for...
Ubuntu doesn't automatically make restore points so if you did not do a backup before upgrading there's no way to rollback...The other half of the question is for driver savy folks...Not me. Good Luck!

When you say OS 12.04, are you talking about Ubuntu? How far into the boot process does it get? Can you chroot into the installation? (to check on the contents of fstab, and see if your root partition is somehow misidentified?) Is your root partition a whole disk, or a partition on a disk? We need more information to help.

disk drive for / is not ready yet or not present
 

In fstab, it is showing like
UUID= <some number> / error=remount-o 0 1
When viewed using live cd, it is showing like "NO / entry found in fstab"
using chroot, #chroot /mnt/sysimage it dint work....