Go to contact list search any name in your contact list and edit that contact and save after that press right nevi key . MOBILE WILL AUTOMATICALLY RESTART . SO DONT BUY THIS MODEL ANYWAY. . ITS FAILURE MODEL .And also I gave to samsung service centre.THAT WILL ALSO VERY BAD SERVICE CENTRE. . .SO DONT BUY THIS MODEL ANYWAY. . ITS FAILURE MODEL .ITS FAILURE MODEL . ITS FAILURE MODEL . ITS FAILURE MODEL . ITS FAILURE MODEL .