NokiaLumia 820 / Lumia 920Mobile phoneResetting to factory settings
Important: Resetting the mobile phone will delete all saved data and settings. Some problems may be resolved by simply restarting the telephone. Another possible solution is to install a Software-Update.
Recommended: Save your data using Zune, before resetting your Nokia Lumia 820/920.
The following steps contain instructions on how to reset your Nokia Lumia 820/920.
Go to the Start screen.
Scroll to the right.
Choose reset your phone.
Your Nokia Lumia 820/920 is reset to factory settings. The device will reboot.