Hello and Welcome. My name is Michael.
There a couple of fixes that could get your phone working again....let's try the easiest one first which is the Force Restart:
In the unlikely event that your device becomes unresponsive, frozen, blank or black screen, or will not respond to the power button, you can perform a force restart or reboot on the device by following the steps below.
Press and hold the Power button for 10 - 20 seconds, the device will restart and go through the boot-up sequence.
If that fails to get your phone working then you need to do an External Reset:
If you are unable to access the phone's menu to perform the standard reset you can attempt an external factory reset.
When using this feature; everything is deleted from the device.
Reset will require a minimum battery level of 25%. If you are unable to perform a reset, please charge for 20-30 minutes and try reset again.
Please let me know if I can be of further assistance.