When you say "stuck" what do you mean? Is it not responding at all? If that's the case, chances are you'll need to wait for the battery to die, honestly.
If you can still access the interface to some degree, you'd need to enable usb debugging (through "Developer Options") and run "adb reboot" from your PC with ADB installed. I can give you some more details there, but it's not worth it if your phone is truly locked up.
