Other titles for this same problem.
- I have changed my hard disk boot order and GRUB no longer boots.
You should enter your BIOS setup and tweak the hard disk boot order so that the right hard disk boots in the first place. You should check that your Hard Disk cables are connected ok.
If you do not want to change the hard disk boot order then you will have to rewrite your menu.lst so that it reflects your new setup.
Finally you will have to reinstall GRUB to the right MBR. Depending on your setup you might need to use the EASY LIVE SWAP option and then the Fix Boot of Linux (GRUB) option or just only the Fix Boot of Linux (GRUB) option.