Looking into this forum there seem to be quit a few people that struggle with Grub after windows (re)installation or other MBR problem
Here is a simple solution that will fix the problem in most cases:
First you need to gain root access.
1# boot-up computer with Ubuntu Installation CD
2# At “boot:” prompt, add “rescue” to the argument
boot: rescue
3# Follow the instructions on screen
4# Now, Assumed that /dev/hda is the location of /boot partition type:
grub-install /dev/hda
If all goes well Grub-menu is back. Just reboot and enjoy Ubuntu agian…
