You may need to reset it. While a hard reset deletes all your information, you can clear the system cache which does not erase any personal data or settings. This feature allows for clearing of all application/background "cache" .
To clear the system cache to reset the phone, follow these steps:
Turn off the device.
Press and hold both Volume Up and Volume Down keys at the same time.
Press the Power key only until the phone vibrates once, then release only the Power key.
Continue to hold the Volume up and Volume Down keys until the Android System Recovery screen appears.
Press the Volume Down key to highlight Wipe Cache Partitian.
Press the Home (or Power)key to select.
Make sure Reboot System Now is highlighted and press the Home (or Power)key to reboot.