If you are unable to send text messages from your mobile handset or people are text messaging you but you are unable to receive them.
Follow the below troubleshooting steps:
Identify the error message that you're receiving? (Usual error is "message sending failed")
Ensure that you have coverage and that you are sending the sms to a valid number.
Try reset network settings, hard restart of the device, re-seat SIM etc.
Test sending an SMS
With the help of a friend or family member, try sending a test Text message to your number and check if you can receive it.
Switch your mobile handset to “Flight Mode” then wait a few seconds and switch back to normal mode.
Try power-cycling your mobile handset.
Try reset network settings, hard restart of the device, re-seat SIM etc.
If none of the above works, try a factory reset.
If this still doesn't resolve the issue, try a different device.
If another device works, then your mobile handset may need to be replaced.