Hey - The touchscreen is completely unresponsive? This normally indicates that the touchscreen has failed electronically. You will most likely have to have it replaced. This is more true if the phone responds to dimming and lighting the screen by short pressing the power button. If short pressing the power button will not work, then try to press and hold the power key for 8-10 seconds to force restart the phone, and then observe if the touch issue will have gotten better.