Recently my hard disk went bad (some bad sectors developed), my boot.ini (Windows XP boot file) corrupted. I was using NT boot loader to load Linux. So I need to repair the Grub i.e. restore Grub in master boot record (MBR).
Today is national holiday (I-DAY) and I wanna watch TV. Problem is neither I can boot to Linux nor using XP. So I just took my Debian GNU/Linux DVD and booting started when I had presented installation option (after networking dialog prompt) :
1) Press ALT+F2 (or ALT+CTRL+F2) to get shell prompt
2) Then get the partition tables for the devices using fdisk command:
# fdisk -l
3)When you type fdisk -l, you should see your partition name: /dev/scsi/host0/bus0/target0/lun0/part1 (for IDE disk it display same device file in IDE directory)
4)Once you identified your device file, mount disk using mount command:
# mkdir /mydisk
# mount /dev/scsi/host0/bus0/target0/lun0/part1 /mydisk
5) Next use chroot command to start interactive shell with special root directory i.e. /mydisk will act as root directory.
# chroot /mydisk
6)Use grub-install command to reinstall grub (SCSI disk):
# grub-install /dev/sda
If you have IDE device following command :
# grub-install /dev/hda
Again replace /dev/hda and /dev/sda with your actual device names.
7)Type exit and reboot the system. You should see your GRUB and Linux again.
Other choice was to use Linux Live CD (e.g. Mepis) and do the above procedure. Well, I could have used the Mepis to watch TV but I had some data and emails in Tunderbird so I opted to restore the Grub; watched TV, took backup of emails and now I will put new 120 GiB hard disk tomorrow :D