I have always been able to send text mags to non Apple users from my iPad. Now all of a sudden I cannot. Why

That means that you have an iPhone and you are using text message forwarding. Did you check the settings on the phone? Settingd>Messages>Text Message Forwarding>Your iPad name>On. If it is on and its still not working, try tuning it off, then restart the phone and turn it on again. You will have to enter the code that the phone sends to the iPad in order to complete the process.

You do have an iPhone correct? There is no way that you can text with non Apple devices unless you text via text message forwarding on your iPhone.

Brilliant. I've struggled for 24 hours trying to figure it out and in two sentences you fix it exactly. Thank you!!

I'm glad that I was able to help.