USB Mic not detected

Hi. I am on Mac 10.14.6 with Audacity 2.3.3. I had a problem with the USB mic not being detected in a previous version of Audacity. So I downloaded 2.3.3 and it worked fine. It detected the USB mic. Now 2 days later, it does not detect the USB mic. System Pref sees the USB mic, but Audacity Pref does not. Any ideas?

OK. It looks like I have solved this problem simply by shutting down the computer and rebooting. However, that has led me to another problem which I have to investigate. I may be back.