I cannot receive any sms/mms messages but I can send? what could the problem be?

Hello Nickster1963,

Thanks for using Apple Support Communities.

For more information on this, take a look at:

iOS: Troubleshooting Messages

http://support.apple.com/kb/ts2755

To resolve issues with sending and receiving SMS, follow these steps first

1. Go to Settings and turn airplane mode off.
2. Verify that you have a cellular network signal in the status bar at the top left of your iPhone. Learn more about troubleshooting no service if there's no signal.
3. Restart your iPhone.
4. Tap Settings > General > Reset > Reset Network Settings on your iPhone.
5. Reseat your SIM card.

Best of luck,

Mario