This article describes how to perform a factory reset.
INSTRUCTIONS & INFO
A master 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.
From the home screen, tap Menu.
Swipe to, then tap Settings.
Scroll to, then tap Reset.
Enter the password. Note: The default password is 1234.