From Factory Reset
Nokia Lumia 900 Factory Reset Instructions
- Go to Settings.
- Scroll down to the About listing and tap on it.
- At the bottom of the screen (you may have to scroll) you'll see a button titled "Reset Your Phone." Tap on it.
- Confirm, twice, you are sure you want to reset your device.
- Turn off your Nokia Lumia 900
- Press and hold the following buttons Camera + Volume down + Power until your phone vibrates, then release only the Power key and keep pressing the Camera + Volume down for a couple of seconds 4-5s.