Insert the installation media {DVD/USB}.
Set the BIOS to boot from installation media.

Choose or type ‘linux rescue’ on the first screen that appears.

On reaching the shell type :

#  chroot   /mnt/sysimage

Now, check the name of your hard disk :

#  fdisk   -l

Let the name be “sda

#  grub-install   /dev/sda

This will install the GRUB on MBR. Now, reboot the system and remove the installation media.