i don't know a lot about the internal details for HDDs and things like that, but id guess that for your data recovery maybe switching out the connector of the drive itself might work, or else maybe when you dropped it some of the connections inside the HDD came loose. I think maybe  try dismantling the drive and checking each component individually to see if they still work. with most broken stuff (like with a psp, ipod, laptop, etc.) its something stupid like a connector wire fell out or something.