loadkeys it
mount -o bind /dev /mnt/sda1/dev
mount -t proc none /mnt/sda1/proc
chroot /mnt/sda1 /bin/bash
grub-install /dev/sda
/usr/sbin/update-grub

SE GRUB DA ERRORE
/dev/sda1 does not have any corresponding BIOS drive.

allora usa il seguente comando:
grub-install –recheck /dev/sda