Newer Grub

For newer grubs use grub-setup.

• boot from Knoppix
• mount /dev/hda3 /media/hda3
• mount /dev/hda2 /media/hda3/boot
• chroot /media/hda3
• grub-setup -v /dev/hda

Fancy things, such as the graphical background, will be lost, but the machine should be bootable.

If, on boot, you get "grub rescue" don't try commands such as help as suggested on the Internet, they will say "help: command not found".  Do this:

• ls
• ls (hd0,5)/boot (or whatever filesystem ls tells you is the right one)
• ls (hd0,5)/boot/grub
• set prefix=(hd0,5)/boot/grub
• set root=(hd0,5)
• set normal