Press and hold the power button
Tap Restart or Reboot if it appears
If no restart option appears, tap Power off
Wait until the phone turns off completely
Press and hold the power button again to turn it back on
If the phone is frozen, press and hold the power button and volume down button together until it restarts
If that does not work, remove the battery if your phone has a removable battery, then reinsert it and turn the phone on