How do I unlock my motorola backflip screen?

I got a motorola backflip phone a few days ago, and it has been working fine, but about an hour ago, the screen locked up. I tried pressing both unlock buttons, but it didn't work, and I tried to turn off the phone, but it won't turn off. It doesn't respond to the touch screen or ANY of the buttons on the phone. What do I do? How do I unlock it?|||Take the battery out and then put it back in again.