From the home screen press the Center key. Scroll to Setting and press the Center key. Scroll to Others and press the Center key. Scroll to Airplane Mode and if off press the Center key. Press OK. Scroll to Off and press OK. Reset the network settings.
Resetting the network settings reconnects your phone to the network and does not erase any of your content or data.
If the problem occurred after you follow the guide, just try to replace your sim. Good Luck!
Answers & Comments
Try this guide
Verify airplane mode is turned off.
From the home screen press the Center key.
Scroll to Setting and press the Center key.
Scroll to Others and press the Center key.
Scroll to Airplane Mode and if off press the Center key.
Press OK.
Scroll to Off and press OK.
Reset the network settings.
Resetting the network settings reconnects your phone to the network and does not erase any of your content or data.
If the problem occurred after you follow the guide, just try to replace your sim. Good Luck!