How to Hard Reset the Sprint HERO

A master reset restores the original factory settings and will erase all downloaded content, including ringtones, contacts stored in the handset memory, etc. It does not erase data stored on the SIM card or memory card (if available). Back up all necessary data on the device memory before proceeding.
Menu Path Method:

1. From the Home screen, press the Menu Button and select Settings.
2. Select Security.
3. Select Factory data reset.
4. Select Reset phone.
5. Select Erase everything.
6. The device will dump all of the data and reload.

Key Stroke Method

1. Power the device OFF.
2. Press and hold the HOME and Back Arrow buttons. While holding these buttons, press the End Call button once.
   Release the Home and Back Arrow buttons and press the Trackball to execute the Hard Reset.
3. The device will reboot once the process is complete. 
   You can also perform a factory reset by using the phone buttons. When the phone is turned off, press and hold the HOME, END CALL/POWER, and BACK buttons. The reset process will start after a few seconds. When the phone finishes the reset process, press MENU.