Samsung SPH-M910CAAVMU - Manual (Page 124)

Settings 117
Resetting Your Device
Resetting the device restores all the factory defaults,
including the ringtone types and display settings. All
data, including downloaded applications are deleted.
Important!: Back up your important data before you perform a
factory reset of the device.
Press ➔ and tap ➔ Privacy ➔ Factory
data reset. (You will see a disclaimer.)
3. Read the disclaimer and tap Reset phone.
4. If you are certain that you would like to restore
all factory settings, tap Erase everything.