Reinstalling Grub legacy Linux boot loader. If you have accidentally removed Grub or you set up a dual boot and Windows did here is how to restore it.
1. Boot into a Linux live cd.
2. Make the mount point directory.
3. Mount the partition(s) of the disk your working on.
sudo mount /dev/sdxx /mnt/recovery
(sdxx being the partition to be mounted i.e sda1).
sudo mount /dev/sda1 /mnt/recovery
Install Grub (yum needs to be substituted to the package manager of your distro, yum, aptitude etc. In this example we will use yum.
chroot /mnt/recovery yum install grub -y
4. Reinstall Grub boot loader to the MBR.