I
I assume that its on- Press and hold the home button and the power button at the same time until the screen goes black and the apple comes up- then let go- this reboots your device and should help if the screen is frozen
Yeah, just note that the above is a "hard reboot" and an Apple agent even told me to never do that unless it is a last-ditch effort. So, before doing that, I would just try holding the power button down first and see if the power off slider comes up. Then if it doesn't, take this route.