How to Recover Broken Bootloader

when ever we decides to make our computer dual boot we may face various problems. One of this problems is operating system selection menu  is not coming.if we install Microsoft operating system after installing any linux kernel base system. we can easily restore the OS selection menu.

How to do it through Floppy disk.

Insert a blank floppy disk in your floppy drive.

Windows

• download rawwritten  program.
  
• With button choose the SGD floppy image.
• Click on Write button.
• Wait till process is complete.

Linux

Execute following command .

dd if= path to floppy image of=/dev/fd0.

wait till copy process is complete.

If you are using USB floppy drive then output will be /dev/sdb or similar rather than fd0 .To see  correct name run df   command,  the output will show you the correct name for your floppy disk .

if you have USB Drive:

The best part of this method is that you dont need to delete any of your file on your usb disk and you can use any of your working line system, if you  dont have one then even you can use live cd to boot your computer and this method will work.

1. insert your USB stick.
2. your usb drive should automatically get mounted if not try mount it with mount comand.
3. run df  command to see on which partition your usb drive is mounted , the very first entry in the output shows the requisite details. it should be like /dev/sda or any of the sd. lets us assume that it is  sda1.
4. download Super Grub Disk  and untar it into a temporary directory. (untar command is tar -zxvf directoryname.tgz)
    
5. Copy and paste the boot folder found in the USB tar so that when opening your pendrive you see: boot (You should not see super_grub_disk_0.9753 or something similar).
6. close the pen drive and right click on the usb disk icon on desktop.
7. click unmount and dont click safe extraction.
8. open a terminal.
9. get sudo permission. by executing command sudo in ubuntu and su in other systems .
10. let us assume our usb drive was sda1 so we will executing following commnads.

11. grub
    grub>device (hd3) /dev/sda
    grub>root (hd3,0)
    grub>setup (hd3)
    

where sda is the hardisk partition where sda1 is located , by executing above command we have attached a virtual drive hd3 with it and worked with it.

you should see some messages with some normal errors.

now exit from grub by executing following commnds.

              grub>quit

      sync

             Now unplug your usb device.

Common errors

If you were doing:

grub>root (hd3,0)

grub>setup (hd3)

and after that you got an error 18 or something similar you should:

Backup all data on your pendrive (if there is something important ;) )

Repartition it so that you have an ext3 or a FAT32 partition at its beginning of only 300 MB.

Install SGD into it as it is explained in the instructions

             and that's it, SGD should boot without problems.

Windows

Download unet

• Run Unetbootin. Select Distribution, and from the drop down menu select "Super Grub Disk"

  Select the target drive, and hit OK.

Fedora

Whenever we run:

grub>setup (hd3)

you can see something as:

setup (hd3)
 Checking if "/boot/grub/stage1" exists... yes
 Checking if "/boot/grub/stage2" exists... yes
 Checking if "/boot/grub/e2fs_stage1_5" exists... yes
 Running "embed /boot/grub/e2fs_stage1_5 (hd3)"...  26 sectors are embedded.
succeeded
 Running "install /boot/grub/stage1 (hd3) (hd3)1+26 p (hd3,0)/boot/grub/stage2 /boot/grub/grub.conf"... succeeded
Done.

Fedora is using grub.conf instead of SGD's menu.lst.

Just after running setup you must identify the install line and modify it so that /boot/grub/grub.conf reads: /boot/grub/menu.lst

In the former example it would be:

grub> install /boot/grub/stage1 (hd3) (hd3)1+26 p (hd3,0)/
boot/grub/stage2 /boot/grub/menu.lst

Then you just continue with the next howto step.

Tagged as: Bootloader Recovery, GRUB recovery, LILO recovery, LINUX