Wrestling with this difficulty all day, finally, this evening, I found the answer–I’m pretty sure it’s the answer–on a WordPress Help site, under “Sharing.”
What could be simpler? Somehow my blog’s connect to Facebook got accidentally disconnected. All I had to do was click a “Reconnect” button. Now let’s see if that has put me back in business. I think it will.
I thank you all for your patience.