Hello Gloria,
To be able to restore factory settings, you can follow the steps given below:
- Press and hold the Volume down and Power buttons at the same time until you feel a vibration.
- When you feel the vibration, release the buttons, and then immediately press and hold the Volume down button until you see a large exclamation mark.
- Once the exclamation mark appears, press the following four buttons in this order: Volume up, Volume down, Power, Volume down. Your phone should now reset and restart itself. (It might take a while for the reset to finish.)
Note that resetting phone will erase all content stored on your phone so makes sure that you backup your stuff.
Let us know how it goes.