Does the computer have a floppy drive? If so, you should be able to use a working computer to create a bootable floppy, then put GetDataBack on it. Run the program and see what, if anything, it says it can do with the bad hard drive. If that doesn't seem helpful, you might trying buying a copy of Norton SystemWorks or something similar.

Once you get it working again, I strongly recommend using something like Carbonite to keep the hard drive backed up in case something like this recurs.