Samsung Galaxy Prevail M820 Android hard reset1. Power off M820 Prevail or take out battery and reinsert it.
2. Press and hold VOLUME UP and POWER ON your phone.
3. When you see Samsung logo release ONLY Power button but keep pressing Vol UP.
4. When you see recovery menu release VOL UP button.
5. Select Factory reset with Vol down and press camera key.
5. Select Yes.
Resetting Your Phone
Resetting the Galaxy Prevail™ restores all the factory defaults, including the ringer 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.
1. Press > and tap > Privacy > Factory data reset. (A disclaimer displays.)
2. Read the disclaimer and tap Reset phone.
3. Tap Erase everything to restore all factory settings.
Use this method to hard reset your Samsung Galaxy Prevail Android phone: Enter *2767*3855#. Warning! All your data including contacts, messages etc. will be lost! Copy all your necessary data/Contacts/Messages etc. to SIM or make backup to your PC before full reset! Take out SIM card before full reset.
What to do if you forget the Samsung M820 Prevail pattern:
If you fail to draw the correct unlock pattern on the screen after five attempts, a prompt displays and you must wait for 30 seconds before you can try again.
1. Tap Forgot pattern.
2. Sign in using your Google account name and password, and create a new screen unlock pattern.
If your M820 Prevail frozen just take out battery and reinsert it, then, position the battery cover over the battery compartment and press down until you hear a click.