My iPad will not respond to touch at all. I can’t even shut it off. What do I do?

Try force restarting the iPad. See this for instructions, depending on your model. Restart iPad - Apple Support

What year and model iPad do you have/own?

The “A” model number can be found on the aluminium back of your iPad, in small print, right under the larger bold print “iPad”.

What iOS/iPadOS version is this iPad, currently, running?