Hard Reset NOKIA Lumia 521
- Switch off your phone.
- Next press and hold together Power button + Volume down
- Release Buttons when device will vibrate.
- When you will see exclamation mark press this sequence of keys: Volume Up -> Volume Down -> Power button -> Volume Down
- Device should now restart.
- Done, handset is now ready to work on.
How To Hard Reset Nokia Lumia
Help! This doesn't work
Hard Reset will erase all of your data
All described operations you are doing at your own risk.