Recently my Lumia 920 froze and became unresponsive, while I was playing Galactic Reign. The phone became completely unresponsive, the Windows key, the back button nor the display would respond to my commands. I could not even turn the device off by clicking and holding the power button. I tried plugging the device to a power outlet and to my computer , they had no effect. Now since we cant remove the battery the only other choice I had was to let the battery run dry. I am not sure if any of you have seen a similar issue with your Nokia Lumia 920 , or any other Windows Phone device.
When I searched the internet for a solution I came across the soft reset and the hard reset key combination which might work. I decided to go with soft reset first since that does not wipe any data from the device. Press and hold the power button and volume down button for about 10 seconds and your phone will reboot.
Soft Reset Lumia 920
It might work on other Lumia and Windows Phone devices. Let us know if this works for you.