Try to reset your phone. Hold the sleep/wake button at the top right and the home button at the same time. Keep holding until the screen goes black.Once the Apple logo appears let go of the buttons, your phone should now reboot. If that does not work, (Always make sure that you back up your phone promptly so as to minimize any loss of important data). After you back it up you could also try a restore. If that does not accomplish anything, it may be time to disassemble your phone, clean the digitizer & LCD connectors with a Q-tip and isopropyl alcohol, and then try reconnecting the digitizer & LCD connectors, if that does not work then consider in buying a new digitizer/LCD assembly. Hope this resolves the problem, good luck.