Unable to restore iPhone 5 after it dropped
Error 21 indicates issues with the power source/battery, error 2002 usually is a connection problem. Given the fall your phone did, it's a safe guess that something broke or got disconnected on the inside.

It's probably best to go to your nearest Apple Retail Store (if this is an option), your vendor or a local iPhone repair shop. If you are used to fixing electronic devices yourself, you may also find instructions on ifixit.com (search for the error number).