I recently installed and used a Python program, internetarchive. Somewhere along the line of installing it with pip, the Python setup on my machine got changed, not in a good way. Lots of Python programs are apparently very sensitive to Python version numbers.
The symptom was that sound stopped working on my system (except in Zoom, which evidently handles its own sound subsystem). Then, sound menu wouldn't come up. Then the Cinnamon system settings control centre, cinnamon-settings, wouldn't come up. It generated an error saying that it couldn't find "requests." At another time, it couldn't find "urllib3".
Cut a long story short, running
sudo apt reinstall requests urllib3
fixed the problem.
