The easiest way to restore a broken system’s GRUB2 files is simply to replace them. This works with Ubuntu 9.10 or later only and only if the system uses GRUB2 (which it does if it was originally installed using 9.10 or later, but might not if Ubuntu was originally installed using an older Ubuntu release and upgraded as GRUB2 is not automatically installed during release upgrades).
To get started, boot using the live DVD and open a terminal from the menu at Applications, Accessories, Terminal. Then determine which of the hard drive’s partitions holds the Ubuntu installation, which you can discover using the following:
matthew@seymour:~$ sudo fdisk –l
Unless you customized your installation, in which case you probably ...