If you haven't backed up you data, before trying anything else I'd recommend you boot from the CD that came with your Macbook and try to access you hard drive that way. If it works, and you can see your data, back it up to another hard disk or USB drive as soon as you can.
Once that's done then I'd go about trying to fix the hard drive.
If you don't mind me asking how did you break the "A" key?