You can hard reset a Samsung Rant by following the steps outlined below. You should be aware that you'll lose all data that you've stored on the device, so you should back up anything you need to keep.
- From the home screen, press the OK key.
- Scroll down to settings and press OK again.
- Scroll to more and press OK.
- Go to security and press OK.
- Enter your user lock code using the keypad. (it's the last four digits of your phone number).
- Scroll to Erase/Reset and press OK.
- Go down to Reset Phone and press OK.
- Read the final warning and press OK.
- Scroll to Yes and press Ok.
- Scroll to Yes and press Ok.
- The Samsung Rant will now perform a hard reset and will restart.
As you can see, it's pretty east to hard reset your Samsung Rant, but like I say, make sure you've backed up everything you need to keep before doing it!