Hello
I'm sorry you're having some issues with your phone and texting service. If you haven't yet, try resetting your network settings (you might have to reconnect to any wi-fi networks after that, but no other information will be affected). It's in your Settings - General - Reset - Reset Network Settings, if that doesn't help, try a hard reset (no information will be lost) by holding your home and power buttons at the same time for 10 seconds.
Let us know if you're still having problems with texting.
Thank you,
Dmitriy