macmag, you will have to do a hard reset. That means you '''will lose all your files'''.
1. Turn phone offf
2. Press '''and hold''' the volume up button
3. Press the power button until it says "Samsung Prevail" while holding the volume up button
4. Hold the volume up button until it comes up with "Android system recovery"
5. Using the down volume button scroll to "wipe data/factory reset"
6. Press the camera button to select it
7. Using the down volume button scroll to "Yes -- delete all user data"
8. Press the camera button (remember this erases all data and returns it to original factory settings.
9. Select "reboot system now" by pressing the camera button
10. Phone will turn off and back on.