Yesterday, after a lot of WiFi tethering and heavy use of the Lumia 920, the phone finally hung on me. On my drive back home, the device seemed to try restart on it’s own and got stuck in the startup screen with the Nokia Logo. I couldn’t do anything much while driving to get the device back in operation.
Once I got back, I tried the regular method of trying to shutdown the phone by keeping the power button pressed, but that didn’t help even after keeping the button pressed for a long time. After some googling, i found that the Windows Phone equivalent of Ctrl+Alt+Del is actually Volume Down and Power button.
So to restart your non-responsive Windows Phone device, all you need to do is to simultaneously press the Volume Down and the Power button, and keep it pressed till you see the phone shut down or you feel the phone vibrate quickly a few times. You can then release the buttons and then press the power button to start the phone again.