how do I get back the 3 word texting prompt in iphone?

I had it and it went away

Welcome to iMore! I think ours referring to predictive typing on your keyboard. It's pretty easy to get back:
1. Make sure "predictive" is enabled in Settings > General > Keyboards.

2. Open up Messages and start a message. If the word predictions still aren't there slide up from the middle of the keyboard.

You should be all set now: