A device restore may help with a blank or frozen screen, apps crashing or freezing, keypad/touchscreen problems, can't hear, device making noises and device won't sync.
Perform a restore only if absolutely necessary as it removes all data including:
Good to Know:
Follow the step-by-step instructions provided for to restore your iPhone to factory settings.
Allow several minutes for the reset and reboot processes to complete.
If you can't restore your device, try placing it into recovery mode.
To set up the device after the restore has completed, refer to initial setup support.