To restore phone settings to the factory default values in the boot program:
Unplug the phone until it goes dark, and press and hold the volume UP and volume DOWN arrow keys at the same time and plug the phone back in. Hold the UP and DOWN arrow keys until "NETWORK SETTINGS?" appears.
Press NO until "TOOLS AND FEATURES?" appears on the display, and then press YES.
Press NO until "RESTORE DEFAULTS?" appears on the display, and then press YES. "STORE CHANGES?" appears on the display.
Press YES. The factory defaults are restored and the phone reboots for the changes to take effect. When the date and time appear on the display, the phone is ready for use.