Sorry to hear about what happened to your phone. Are you positive that the error you're experiencing is due to dropping the phone? You may want to try reinstalling the device software to rule out any software errors before you decide to do a repair. However, if you physically damaged your device, and now the touchscreen isn't working, chances are you damaged the touch screen digitizer. Sadly, the display and digitizer are a single assembly, so you'll need to replace both to fix your device.