I'm passing on something I just learned.

I was unable to join the last Mudcat Singaround because Zoom put up a box claiming "Failed to find microphone and speakers." I spent two hours trying to fix that by using menus, checking settings, asking Google and checking cables. On Wednesday I had a Zoom meeting with a club, and I spent an entire hour trying to hear that meeting.
It remained silent.

I tried to call Zoom, but they wanted my Personal ID, which I couldn't see unless I joined a meeting, and I couldn't get on a meeting because Zoom's box wouldn't let me past.

Finally, among a lot of useless Internet tips I found the suggestion that I uninstall Zoom and install it again.

That's what fixed it. Everything at my end was fine. The problem came from Zoom, probably something wrong in an update. I uninstalled Zoom and tried to re-install almost immediately, but Zoom put up a fight. The next day, however, the re-installation worked perfectly. I guess it can take a while for a corporate giant's records to catch up to what a consumer has done. (This is a good thing to know for computers in general.)

I asked a friend to set up a Zoom meeting just for the two of us, and when I signed in, everything worked just fine. I plan to be at the Singaround tomorrow.