Before you buy a new cell phone or new tablet, please try the following procedure to repair your device. First charge your battery, backup your important data if possible and in most cases take out SIM and SD card before factory reset. It is impossible to recover your data after doing a hard reset, so online backup is always important. For all of your data, a backup should be done on an external device, hard drive, raid system or media. With or without insurance, if your cell phone lost, damaged or stolen at least your invaluable data is backed up in a safe place. If you are about to sell your phone and you want to wipe your personal data, or if your phone affected with virus you have to do a hard reset. In some cases, you can delete the forgotten password or lock pattern from your device as well. All information is for devices with stock based ROMs. If you are using rooted device, always back up your EFS folder first, containing your IMEI info, etc.!
Nokia Lumia 800 hard reset
Hardreset via Keys: Charge your phone. Turn off your Nokia 800. Hold Volume Down + Camera + Power Release Power, but hold Volume Down + Camera for 5 secs. Release buttons Phone will start with factory settings without prompting
First try this to soft reset your Nokia 800 Lumia. Press and hold the Volume down and Power buttons until it vibrates, after that you have to release all the keys then phone will vibrate 3 times.
To hard reset your Nokia Lumia 800 using key combination
Turn off your Nokia Lumia 800. 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.
On the Start screen, tap .
Tap Settings > about phone.
Tap reset your phone, and then tap yes.
Repair Nokia Lumia 800 do one of the following • Reboot your Nokia 800 phone. Press and hold the power key for about 10 seconds. The phone switches off. To switch your phone on again, press the power key. • Update your phone software • Restore the original factory settings