Hi, I too had the same problem, I couldn't restart or switch off the phone as if it lost the screen sensitivity. I've pressed the lock/unlock button on the right side continuously for a while and then it got switched off. I've then restarted it using the same button, now its working fine.
Same issue happened for me. I have long press the power button (right side button) for 2-3 mins and phone got switched off and restarted and now its back to normal. Volume and power button is working fine :)
