Substitute the correct partition: sda1, sdb5, etc. sudo mount /dev/sdXY /mnt Example 1: sudo mount /dev/sda1 /mnt Example 2: sudo mount /dev/md1 /mnt Only if you have a separate boot partition (where sdXY is the /boot partition designation): sudo mount /dev/sdXY /mnt/boot Example 1: sudo mount /dev/sdb6 /mnt/boot Example 2: sudo mount /dev/md0 /mnt/boot Only if (some) of the system partitions are on a software RAID (otherwise skip this step): make sure the output of mdadm --examine --scan agrees with the array definitions in /etc/mdadm/mdadm.conf. Mount the critical virtual filesystems. Run the following as a single command: for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done Chroot into your normal system device: sudo chroot /mnt Reinstall GRUB 2 (substitute the correct device with sda, sdb, etc. Do not specify a partition number): grub-install /dev/sdX If the system partitions are on a software RAID install GRUB 2 on all disks in the RAID. Example (software RAID using /dev/sda and /dev/sdb): grub-install /dev/sda grub-install /dev/sdb Recreate the GRUB 2 menu file (grub.cfg) update-grub Exit chroot: CTRL-D on keyboard Reboot. sudo reboot