Fried your Master Boot Record?

No worries! You are using GRUB (GRand Unified Bootloader) aren't you?

You should atleast know where your "/boot" partition is installed.

1. Here is my drive setup and "/boot" is setup in "hda3".
   

   # df -h
   Filesystem            Size  Used Avail Use% Mounted on
   /dev/mapper/VolGroup00-LogVol00
                          18G  4.3G   13G  26% /
   /dev/hda3              99M   19M   76M  20% /boot
   none                  506M     0  506M   0% /dev/shm
   

   # fdisk -l
   
   Disk /dev/hda: 60.0 GB, 60011642880 bytes
   255 heads, 63 sectors/track, 7296 cylinders
   Units = cylinders of 16065 * 512 = 8225280 bytes
   
      Device Boot      Start         End      Blocks   Id  System
   /dev/hda1               1        1044     8385898+   7  HPFS/NTFS
   /dev/hda2            1045        4699    29358787+  83  Linux
   /dev/hda3            4700        4712      104422+  83  Linux
   /dev/hda4            4713        7296    20755980    5  Extended
   /dev/hda5            4713        7296    20755948+  8e  Linux LVM
   

2. Boot up your handy knoppix and run the below commands [ notes ].

   # su -                    [ root shell ]
   # grub                    [ grub shell ]
   grub> root (hd0,2)        [ specify where /boot partition resides ]
                             [ 3rd primary partition of the 1st HDD ]
                             [ hint: start count from 0 ]
   grub> setup (hd0)         [ install grub in MBR ]
   grub> quit                [ exit the grub shell ]
   # shutdown -r now
   

3. Here's a one line that will do the same automatically.

   # grub-install hd0
   

   You should now have a shiny new MBR.

Related Reading:

• Backing up the MBR
  
• GNU GRUB