Please note that this guide tells you how to recover previously installed GRUB and reconfigure it. But, it does not tell you how to reinstall fresh copy of GRUB.

My laptop came installed with Windows Vista. I then installed Fedora 14 in another drive. However, I installed Windows 7 over Vista (fresh install, not an upgrade). So, Windows installed its own bootloader and grub was gone. So, I could not boot fedora because Windows bootloader could not identify Fedora. So, I had to reinstall grub using the Fedora LiveCD ISO image I had.