I can send texts but I can't receive?

I can send texts but cans receive. How can I fix this? This is an iPhone 4 btw

Do you have direct access to another device that can send and recv texts? Send a test text to the device and then REPLY from the other device to make sure there's a problem. If there's still a problem, contact your service provider. You can always get an alternative app for sending texts messages. I use PINGER… Its free and you can use it send/recv test messages as well.

Reboot the phone… Work now?

if not, call your wireless carrier for a possible network issue

You could try conventionally shutting the phone off and turning it back on again or you could force shut it down. I don't think you will need to force shut it down in this situation though, this would only be necessary in an instance where your phone freezes. If you wish to try force shutting it down, though, you press the on/off button and the home button at the same time until the apple logo appears on the screen. The phone will take it from there! If this doesn't work I would call your provider or go the store you got the phone at and they will definitely help you. Apple is very good with helping customers in a timely fashion. Hope I helped!