Press up volume, power and the screen button simultaneously for a sec or three.
You'll see the normal startup image with some blue text (it'll say recovery booting) at the top of the screen!
This screen will give you plenty of options, depending on the carrier (they all use slightly different versions you know, because), you can do a lot of things from this screen. but for this guide hit "wipe data/factory reset"
You'll be prompted to with an are you sure yes or no!
It doesn't take long, then you'll be returned to the original menu select reboot!
What if your phone doesn't restart? YOU BROKE IT WHAT DID YOU DO!!! HOLY CRAP!!! no its fine pull the battery put back in, you should get the android is optimizing screen.
Once its gets all booted prepare to re-download all your apps and just oh god everything!