In case your phone has a persistent problem that cannot be solved, the last resort is to do a factory reset.
If your phone is running slower than normal, an application is not performing properly, or your phone becomes unresponsive,
try restarting your phone and see if that helps solve the problem.
To restart your phone, simply turn it off and back on. If pressing and holding the POWER button doesn’t work, then remove the battery,
wait for a few seconds, reinsert the battery, and then turn the phone on.
If you cannot turn on your phone or access the phone settings, you can still perform a factory reset by using the buttons on the phone.