Following the installation of Windows 7 on my desktop machine that was previously running Ubuntu 9.04, I realized that one of my partitions was missing. It was formatted as ext3 so of course it wouldn’t show up in windows. When I went to boot back into linux the grub boot manager was gone. The machine just booted straight into windows 7.
To re-enable grub was a lot simpler than I thought it would be. Since the Ubuntu 8.04 install disc that I had lying around also works as a live disc I booted my desktop off that. Once Ubuntu started up I opened up a terminal and typed these commands:
sudo grub root(hd0,7) setup(hd0) quit
I then rebooted and grub was back to normal with both my Ubuntu operating system and windows 7 listed. Note that hd0,7 was the partition where I installed Ubuntu. If you installed linux before windows then you will probably want to use hd0,0. I installed windows 7 over a broken windows xp partition that I had installed before everything else.
If you installed ubuntu before you installed windows then you’re probably going to have to edit your ‘/boot/grub/menu.lst’ file. The grub documentation may be helpful.