It sounds like either the cable came loose, or the keyboard 'died.' You would need to remove the top portion of the laptop's case to lift the keyboard out and check the cable. If the problem is not a loose cable, you will most likely need to have the entire keyboard replaced.
Make sure that the keyboard is not responding in any application, i.e., test it in BIOS or by booting from something other than your hard drive, if you can.