In order to hard reset a Samsung Galaxy Prevail, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Samsung Galaxy Prevail device will be brought back to the default configuration of a brand new device.
1. Turn off the phone by holding the Power button.
2. Press'n'hold these three buttons simultaneously: Volume Up, Power. Let go of Power when the Samsung logo appears.
3. Release the rest of the buttons when the Recovery Mode opens.
4. Now select, in the same way as above, Yes and Reboot system now.
5. Done!