Gray screen on opening existing docs

I was editing an existing WORD for MAC doc & pasted 2 words from an online article. The 2 words I copied & pasted ("hempen home-spuns") were in a Shakespearean quote included in the article, "7 Shakespearean Insults to Make Life More Interesting" (https://www.merriam-webster.com/wordplay/shakespeare-insults).

I pasted the text initially using the match existing formatting option, which worked fine, seemingly. I then deleted one of the words in the quote, and reconsidered whether I wanted to use both words. But instead of clicking undue, I chose to repast the text to look at the phrase again & decide if I wanted to use both words.

However, this time I just clicked paste because I just wanted to think it over & not necessarily use the pasted text . . . and that's when all the trouble started!

My doc then seemingly locked & wouldn't allow me to do any more editing. I closed it & reopened it & was greeted by a grey screen, without any text, and 3 items in the menu bar -- the "Normal", "No Spacing" & "Heading 1" items -- keep flashing.

I tried several times opening other docs by either double clicking or displaying them from a menu listing & clicking open, and in every case, I go a gray screen. When I go to File > Properties, it shows the words & characters are still there.

So, whatever happened when I pasted the text w/o saying match formatting caused a problem in my Word for MAC. Doesn't MS have an app to FIX Word for MAC or at least diagnose what the hell is wrong, along with the steps required to fix the problem?

I'd really appreciate some HELP, ASAP. Thank you. -- Wayne