capacitive touch screens not responding
Old Mobile Phones having such problem but none user consider the fact that capacitive displays can be controlled with very light touches of a finger and generally cannot be used with wet or gloved hand.

also, just Read about Capacitive sensing from this link. You will get idea about Surface and Projected capacitance.

and some mobiles with this technologies stop working or not responding to touch. that was just e-waste though you can open device and learn many things.