I have a Nokia Lumia 5201 and is updated to Windows 8.1. Just resently I drop my phone on carpet and did not damage the screen or anything but the back like always popped off and there went the battery. I think that is the reason my phone is messing up. Now when my phone turns off it changes the time to some time in may and some crazy time that is no where near the actual time. Also just recently I noticed that my phone says SIM invalid I don't even have a sim card. And even though I have no idea how to backup my phone since the windowsphone site doesn't help at all I want to reset it and see if that works. I also was told to press and hold Power Button + Volume DOwn button and it resets it but I didn't see anything happen please help me. Oh and where it says SIM invalid is in the rght hand corner of the home screen where you go to call and text and such.
Read more: How to reset my Windows Phone 8?
