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 mobile network settings.
Please note that all saved APN, Wi-Fi and Bluetooth connections and passwords, you've created, are deleted.
Press Reset settings.
Slide your finger upwards starting from the bottom of the screen to return to the home screen.