iPhone 4 AT&T problems need help?

I have a iPhone 4 and recently got the new ios7 update and just recently my phone started to act up all the sudden my phone won't let me text other iPhone users or receive their text if I'm not in a wifi zone but my phone says I have 3G? Also my phone won't let me go on the internet unless I have wifi but my phone says I have 3G and I haven't went over any data so it should work what should i do?