Cannot send text why?

Have you done a restart? If not, hold down the power button for about 3 seconds and touch restart. If you have done this already, try doing a system reset. A system reset will return the phone to the way it was when it left the factory. It will delete everything on the phone, so make sure anything important is backed up. A system reset, or sometimes called factory reset, is good for a phone once in a while, so to do a reset go to settings and find backup & reset, then choose factory data reset. This should fix your problem. I hope I was of assistance.