I'm not a debian user, but I know you can boot debian w/ GRUB and if you install it, I'm thinking you can make a debian boot floppy? Do that and save it. Then you can use command 'grub-instsall' from the grub command line and re-write your debian boot to the mbr, or while booting w/ the floppy you can use commands to edit yr boot menu and maybe recuperate some of what you lost. At least you won't have a black screen w/ F1...etc.
Long way around, especially if yr not familiar w/ grub, but maybe worth it.