[Ubuntu 12.04] Resolve Grub Boot Problems

If you killed your trusty grub (i.e. by new Install of Windows 8.. :/) you can repair it quite easily:
- Boot with an Ubuntu 12.04 Live CD
- CTRL + ALT + T
sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install -y boot-repair && boot-repair

And click on the repair button! Done!

Source: http://askubuntu.com/questions/333483/how-to-restore-grub-after-deleting-it-from-windows-8-disk-manager