How to Hardware Reset Nokia Lumia 920 ?
If your Nokia Lumia 920 gets stuck in the software its impossible to reboot the Nokia Lumia 920 by removing the battery since its battery is inbuilt. WPCentral just posted the internal repair manual from Nokia which shows how to hardware reset without losing any data or removing the internals. To reboot Lumia 920 manually press both the Volume down and Power key for five seconds to manually reboot the phone. When the Lumia 920 hangs up during any software process it will respond to this hardware button combination which will reboot the phone .
In the case of Lumia 820 when it hangs up just remove the battery and reinsert it. Please remember both of these process does not reset the Windows Live ID or remove any user data.