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 VolumeDown button (located on the right edge) then press and hold the Power button (located on the top-left edge) until the HBOOT screen appears then release.
From the HBOOT screen, select FACTORY RESET.
Utilize the Volume Up/Down buttons to navigate through the available options and the Power button to select.
Allow several minutes for the reboot process to complete.
If applicable, set up your device.