Touchscreen calibration and Administrator password.

I Have a GS2 and GS4 that have both got problems with their touchscreens after a power failure. They are both working still but seem to have gone out of calibration and using a mouse is really inconvenient. I assume there is a feature to calibrate the touchscreens but you will need to be an Administrator which is a problem because they have lost the password and the default password of "admin" does not work....HELP !!!!!