A factory data reset may help with a blank or frozen screen, apps crashing or freezing, keypad/touchscreen problems, can't hear, device making noises, can't make or receive calls, and device won't sync.
Perform a factory data reset only if absolutely necessary as it removes all data including:
Press and hold the Volume Down+Power buttons until the "Factory Hard Reset" screen appears then release.
From the "FACTORY HARD RESET" screen, press the Power button to confirm.
From the "Are you sure your want to continue with erase?" screen, press the Power button to confirm.
Allow several minutes for the factory data reset and reboot processes to complete.
If applicable, set up your device.