I just upgraded Ubuntu and selected the wrong location to install Grub onto. Basically, I installed Grub on /dev/sda1 and not /dev/sda and so I need to repair and installing grub.
I got out an Ubuntu installer cd which is essential a live cd and booted in it up. Then mounted the sda1 partition:
sudo mount /dev/sda1 /mnt
Grub then needs to have access to /dev so:
sudo mount --bind /dev /mnt/dev
To install Grub on sda then:
grub-install /dev/sda --root-directory=/mnt/ /dev/sda
Note: we are using the –root-directory option rather than changing the root directory using the chroot command which sometimes doesn’t work on a live CD.
For a tutorial with more words these two pages might helped you learn more: