Step 1: Read ;)
So what happens when you unplug while on is it messes up the backlight and when you power back on you freak out...but don't freak out!
Get a flashlight or hold under a light and
1. Enter password to get in(this is a pain if you have password enabled, if not go to next step)
2. Hold top button and swipe to power off.
3. Hold top button to power on
Step 2: Did It Help?
I read where some people bought replacement LCD screens before learning this!