A master reset is often necessary if you are experiencing issues, lags freezes etc, and will result in the loss of all data stored on the device including 3rd party applications. This type of reset should only be used as a last resort after all other troubleshooting steps have been exhausted. It is highly recommended that you complete a backup of the device information before proceeding with the steps in this tutorial. With the handset turned off, press and hold the Volume Down key. Note: To turn the handset off completely, remove and reinsert the battery.
Perform a hardware factory reset
With wipe data/factory reset highlighted, press the Power key. Press the Volume Down key to scroll to Yes — delete all user data. With Yes — delete all user data highlighted, press the Power key. After the wipe is complete, press the Volume Down key to scroll to wipe cache partition. With wipe cache partition highlighted, press the Power key.