Resetting a smart phone
After a minor fall yesterday (me ! only bruised knees, thanks for the sympathy) ) in which my HTC made contact with the ground, I was having trouble opening the initial screen and entering my PIN. The effect was as if the screen touchpad had become insensitive. Note that once I had the phone 'open' the touchscreen worked perfectly.
I opened the phone tonight, took out the battery, waited, refitted battery, fired it up and it once again worked perfectly. So for anyone who has a phone they can open and is having troubles, try this reset method.