nixCraft

In old good MS-DOS/Windows days, I used the command fdisk /mbr to
restore Win/DOS MBR. How do I restore mbr in Red Hat Linux? I would like to restore MBR of Linux i.e. default GRUB boot loader

You can use grub-install command to install it. Debain has one more good command called install-mbr. Read the man page of both to see example it is quite easy to use both of them...

You can restore MBR if you have taken Backup before.

You maust take back up of mbr on floppy or any suitable storage device by using follo command:-

dd if=/dev/hdx of=/dev/fd0 bs=512 count=1

Where hdx is your 1st Harddisk partition where you have loaded boot
sector(MBR).

Then install grub, and restore MBR again using:-

dd if=/dev/fd0 of=/dev/hdx bs=512 count=1

So you have restored your MBR and recovered the system .

If you have any query pleasd revert it.