If the phone is not working correctly, you may need to reset it. While a hard reset deletes all you information, you can clear the system cache which does not erase any personal data or settings. To clear the system cache, follow these steps:
These are the correct steps but just for clarification: Clearing the System Cache does NOT delete any personal info. Only background/application cache
1. Turn off the phone.
2. Remove the battery and Reinsert it.
3. Hold the Volume Up and Volume Down keys.
4. Press and hold the the Power key while continuing to hold both volume keys.
5. Release the keys when the Samsung logo appears on the screen.
6. Press the Volume Down key to scroll to delete all cache data.
7. Press the Power key to select it.
8. Wait for a few seconds ad the phone clears information.
9. Press the Power key to select reboot system now.