Repair Linux boot-loader issue

How to Repair, Restore, or Reinstall Grub 2 with a Ubuntu Live CD or USB

Grub 2 typically gets overridden when you install Windows or another Operating System. To make Ubuntu control the boot process, you need Reinstall (Repair/Restore) Grub using a Ubuntu Live CD.                                          

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TERMINAL COMMANDS SHOULD BE CAREFULLY ENTERED

PLAYING WITH SUDO COMMANDS WOULD BE LIKE "hollow-bunnies" TO YOUR PC

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Terminal Commands

Mount the partition your Ubuntu Installation is on. If you are not sure which it is, launch GParted(included in the Live CD) and find out. It is usually a EXT4 Partition. Replace the XY with the drive letter, and partition number, for example: sudo mount /dev/sda1 /mnt.

  sudo mount /dev/sdXY /mnt

Now bind the directories that grub needs access to to detect other operating systems, like so.

sudo mount --bind /dev /mnt/dev &&

sudo mount --bind /dev/pts /mnt/dev/pts &&

sudo mount --bind /proc /mnt/proc &&

sudo mount --bind /sys /mnt/sys

Now we jump into that using chroot.

sudo chroot /mnt

Now install, check, and update grub.

This time you only need to add the drive letter (usually a) to replace X, for example: grub-install /dev/sda, grub-install –recheck /dev/sda.

grub-install /dev/sdX

grub-install --recheck /dev/sdX

update-grub

 Now grub is back, all that is left is to exit the chrooted system and unmount everything..

exit &&

sudo umount /mnt/sys &&

sudo umount /mnt/proc &&

sudo umount /mnt/dev/pts &&

sudo umount /mnt/dev &&

sudo umount /mnt

Shut down and turn your computer back on, and you will be met with the default Grub2 screen.

You may want to update grub or re-install burg however you like it.

Congratulations, you have just Repaired/Restored/Reinstalled Grub 2 with a Ubuntu Live CD!