GRUB 2 recovery

We often come across a condition in which the boot loader gets corrupt. Here are a few steps that will help you recover your GRUB 2 boot loader.
Boot from a live CD or DVD, which supports GRUB 2 (Ubuntu 9.10 CD or above. A DVD will take more time than a CD, so I suggest you boot from a CD).
Open the terminal and run fdisk -l to check the partition from which you want to recover GRUB 2.
Here I assume that you want to recover it from /dev/sda1.
Then run the following commands:
 
sudo mkdir /media/sda1
sudo mount /dev/sda1 /media/sda1
sudo mount --bind /dev /media/sda1/dev
sudo mount --bind /proc /media/sda1/proc
Now chroot into that partition by running the command given below:

sudo chroot /media/sda1

Then re-install GRUB, as follows:

grub-install /dev/sda

The output should be like what’s shown below:

Installation finished. No error reported.

If you get an error, then try the following command:

grub-install --recheck /dev/sda

After a successful installation, exit from chroot and unmount the file systems that were mounted to recover GRUB. Now reboot.

exit
sudo umount /media/sda1/proc
sudo umount /media/sda1/dev
sudo umount /media/sda1
sudo reboot

You’ve successfully completed recovering your GRUB boot loader.

Information courtesy: EFYTimes News