If you can't connect to the internet, send or receive email and/or messages (text, picture or video), resetting the network settings may help.
The following are cleared or restored to default values:
Cellular and Wi-Fi network settings (including saved networks and passwords)
From a Home screen, navigate: Apps icon > Settings.
If Settings is unavailable, tap the Dropdown menu (located in the upper-left) then select Alphabetical. If still unavailable, refer to Manage App Icons.
From the PERSONAL section, tap Backup & reset.
Tap Network settings reset.
Tap RESET SETTINGS (located at the bottom).
If prompted, enter the PIN, password or pattern.