If its frozen & you cannot shut your phone off to reboot it then try pushing the volume up button & the power button at the same time & hold them until your phone shuts off. That is an emergency shut down. Then give it sometime to cool down be4 trying to turn it back on. If it does not turn on again or its still frozen / not working at all when you do, then it most likely has crashed. I've had this issue on a few phones & had to replace my phone. If your under a contract or have insurance then you can get your phone replaced without any cost. You can also have your phone company try a factory reset to see if that helps your phone if nothing else works. That would tell if your phone has crashed or not. Good Luck....