So you are dual booting Linux and Windows on your computer. It used to work just fine. But now, you ‘ve either reinstalled Windows, rewrote the MBR “Windows-repair” way for some reason, or whatever the case, suddenly, no more grub when you boot up. What do you do?
1. Grab an Ubuntu CD and boot from it (not install, just booting … I think the option is called “Try without any changes to your system”).
2. Open up the terminal window
3. type in: sudo grub
This will now change your prompt to “grub>”. All the following commands happen in grub
4. Type in: find /boot/grub/stage1
This should return something like (hdX, Y) where X and Y are some numbers.
5. Type in: root (hdX, Y) (so YES, the numbers, not the letters, fill in X and Y corresponding to whatever they were at 4)
6. Type in: setup (hdX) (same thing here)
7. Type in: quit
Reboot, take out the Ubuntu CD, and you should get grub back with all your previous settings in place. Yup, that’s it.
Acknowledgments: Credits to “catlett” from the Ubuntu Forums