If you have problems using network configurations on your phone, such as mobile data, Wi-Fi or Bluetooth, resetting the network settings may help.
Slide two fingers downwards starting from the top of the screen.
Press the settings icon.
Press Reset options.
Press Reset Wi-Fi, mobile and Bluetooth.
Please note that all saved APN, Wi-Fi and Bluetooth connections and passwords, you've created, are deleted.
Press Reset settings.
Press the Home key to return to the home screen.