I have both Windows 7 and Ubuntu 12.04 installed on my Laptop. For some reason, windows had an error, so it started the repair tool. This was taking a while and so I cancelled it. Now my GRUB screen is gone, when I load up the computer it goes into an infinite reboot state. I can still access the BIOS and Windows 7 and Ubuntu 12.04 both still seem to be there (I am writing this from Ubuntu 11.10, which I have on a bootable DVD). Obviously the last resort is to remove everything and just use Ubuntu, but it would be much nicer to have them both fixed. Is there a way to re-install the GRUB screen or something?
You can reinstall grub and that would fix the problem I guess. http://sosaysharis.wordpress.com/2011/06/29/recovering-grub-after-installing-windows-using-ubuntu/