You can boot from grub manually, then fix up your grub configuration.
You at least know that it is loading stage2, which means that the stage1 file is installed correctly.
find /grub/stage2
or
find boot/grub/stage2
should find your boot partition - should be something like (hd0,0), which is the first partition in the first disk, so /dev/hda1 or /dev/sda1
from there you need to work out what's missing (or broken)
you need either a menu.lst or grub.conf in the same place, and you need a working kernel image (and possibly initrd ramdisk image). You can do all this in grub, but it's not the same as a bash shell.
grub manual here:
http://www.gnu.org/software/grub/manual/grub.html
My guess is that your menu.lst or grub.conf is broken (as a first step, disable any splash images - comment out that line if it exists).
It might be easier to do it from a live-cd though, once you've found out what your boot partition is.
