Musescore bombed after upgrade.

[mahesh]

I was trying to get back into Ubuntu just to use Musescore. I repurposed an old desktop PC for which my wife couldn't remember the password, found an old Ubuntu 20.04 install CD, installed, received some system upgrades, and was stable for a few weeks. I had a picture of a panther on the desktop. I did a few projects in Muscore, my printer worked fine, and I could air drop to my iPad. Today, I took the option presented to me to upgrade Ubuntu. Ended up with a jellyfish. Now Musescore startup gives me a black window. I don't know what it means that the Musescore program circle icon on the left margin of the desktop is rocking. Already tried powering down and restarting. Can I fix this? Can I roll back to an OS version that was working for me. Or should I reinstall from the CD again? I have backups of my Musescore projects on Dropbox so I could be back in business pretty quickly, but I do have a gig tonight.