Same as I posted HERE, this Nokia lumia phones (710, 800, 900, 920) can be hard reset (Reset to factory settings) by doing this simple steps and key combinations:
* Turn off your phone.
* Hold volume down (-) + power + camera until phone vibrates
* Release Power button once the vibrate finish but continue to hold volume down (-) + camera.
* Windows logo will appear for some time wait for it until the boot completes.
* Congratulations your phone has now been successfully reseted and is back to its factory settings.
Take note that this procedure will delete all the contents of your phone so better back up everything before proceeding.
