Why I can't send a text on my iPhone 5

[iMore Question]

I have never had a problem sending text until last 12!hours. I did not update anything or change any settings that I am aware of.

 

[Ledsteplin]

Do you refer to iMessage or SMS? If iMessage, try toggling iMessage off in Settings > Messages. Then toggle back on.
Then Reset Network Settings
Reset Network Settings Settings>General>Reset>Tap Reset Network Settings. You may need to enter your wifi passcode back in afterwards.
If that doesn't work, try signing out of iMessage, then sign back in.
If SMS, try Reset Network Settings. If that doesn't work, you may want to check with your carrier.