reset your phone using the hardware buttons:
1.Press and hold the volume down and Power button at the same time until you feel a vibration (about 10–15 seconds).
2.When you feel the vibration, release the buttons, and then immediately press and hold the volume down until you see a large exclamation mark.
3.Once the exclamation mark appears, press the following four buttons in this order: volume up, volume down, Power, volume down. Your phone should now reset and restart itself. (It might take a while for the reset to finish.)