Boot up into a Live Linux Image.

Mount your old Linux Install, and use chroot to take control of it.

mount /dev/sdc1 /mnt
chroot /mnt

You will get grub-probe: error: cannot find a device for / (is /dev mounted?). if you don’t mount you devices, before attempting to install GRUB.

So mount all devices.

mount proc
mount sys
mount dev

Force GRUB to update it’s configuration file, and re install it back to the MBR.

update-grub
grub-install /dev/sdc

When installing GRUB you need to make sure that you don’t specify a number like you did when mounting, otherwise it will be installed on the partition.

Reboot and your done.