Reinstall GRUB using a Live CD
How to reinstall the Grub using a (any) Live CD:
sudo grub
A grub> prompt will appear
find /boot/grub/stage1
A list of all Linux grubs that were found will be displayed. Use
the one that matches the partition of the grub that is being fixed.
Examples: (hd0), (hd0,2)
Use whatever the computer spits out in the next commands. If it was
(hd0,2) then the commands would be:
root (hd0,2) setup (hd0,2)
A bunch of lines appear with "Checking..." and "Running..." The 2nd
last line should read "succeeded" and the last line should read
"Done."
quit
Restart the system and remove the bootable CD.