My Nokia lumia 920 has locked me out because there are no pin numbers on the lock screen. They are just completely gone. I cant remember what I did before this happened that could have caused it, but I think I updated it. I have tried restarting it, letting it die then recharging it, and taking the battery and sim card out. Also it keeps restarting by itself about every 5 or 10 minutes. Is there a way I can fix it or just completely bypass the lock?