Why is my phone rejecting my PIN number?

[AC Question]

Just now, I've tried many attempts to get on my phone by putting in my PIN number to unlock the screen, only to be denied every time. A warning has now popped up saying that I have four more attempts until the phone resets to factory default and all of my data is erased.

 

[belodion]

Try resetting the PIN it via Android Device Manager from another device.