Hello
How to Hard reset ZTE Z665C
1. Press and hold the volume up and the power button at the same time
2. Release the buttons when the android robot apear
3. Use the volumes button to navigate up/down and the power button to select
4. Scroll down to "Wipe Data/Factory Reset" Press the power button to select
5. Sroll down to select "Yes-delete all user data"
6. wait for the phone to complete then reboot your phone.