Calls and contacts
Apps and media
Cause 2 of 4: There's an error in the operating system on your phone
If there's an error in the operating system on your phone, it may help restarting it.
Solution: Restart your phone.
Restart your phone
Open the Reset key cover.
Press and hold the Reset key with a sharp-pointed object (such as a paper clip) until your phone turns off.
Close the cover again.
Press and hold On/Off until your phone is turned on.