Zug, looks like some serious problem with the HD. You tried doing a low level format? rember to backup your data before you try that as it may remain unaccessible even after that. backup or recover your files on the disk if you can using recovery tools.

Low level format should work if its not a hardware issue and everything have failed to correct the problem. If low level format too fails, that simply means, your hard disk is not usable anymore.