I had installed BURG to replace the GRUB menu even though I had only Ubuntu installed in my laptop. And the crazy me typed sudo rm -r /boot/BURG for some unknown reason and the grub was gone. The machine would boot and stop at grub rescue> prompt.
So after messing around in the #ubuntu IRC channel, found that the only option was to boot from a 10.10 bootable usb and rescue the grub. The commands used were:
mount | tail -1
to find out how the root was mounted and,
sudo grub-install –root-directory=/media/5d0602f1-892d-4ef0-9c7a-71a417aafd3d /dev/sda
to rescue the grub.
Moral of the story: Linux assumes you understand what you’re doing.