Howtoforge published a tutorial about how to repair your Grub 2 on Ubuntu.
How to repair your Grub 2 on Ubuntu
Grub 2 was a long-awaited and very important upgrade over the previous version of the most popular and widely used boot manager in existence. Support for new filesystems, themes, improved splash capability, better internationalization, power-pc booting, dynamic module loading, and scripting support. All this is great, but things can still go wrong and break unexpectedly. This basically means that a bootable partition (operating system) may become inaccessible and this is why Grub v2 offers a powerful rescue mode. Now using this mode, may not be exactly a walk in the park for most inexperienced users out there, so here's a guide on how to easily fix your Grub with the Boot Repair tool.
