Learn how to perform a soft and factory reset of the device.
INSTRUCTIONS & INFO
From the home screen, drag down from the Notifications bar with two fingers to access the menu. Note: A factory reset reverts the device back to factory settings. It will permanently erase all personal data, preferences, settings and content such as pictures, ringtones and apps that are saved to the device. Data stored to an SD card will not be erased unless otherwise selected. It is recommended that you save (backup) important data to your SIM, SD card, or a computer before proceeding.
Scroll to, then tap Backup & reset.
Scroll to, then tap Reset to factory.
Tap Reset phone.
Tap Erase everything.
If unable to reset the device using the above steps, try the Alternate master reset method by first powering the device off.
Alternate Master Reset Method: With the phone powered off, press and hold the Volume up and the Power/Lock key for a few seconds, then release > Press the Volume down key until "wipe data/factory reset" is highlighted > Press the Power/Lock key to select > Press the Volume down key until "Yes -- delete all user data" is highlighted > Press the Power/Lock key to select > Once data has been wiped, with "reboot system now" highlighted, press the Power/Lock key to select.