Calibre Reset to Only 1 Library

When I opened Calibre today, the color was reset, all of menus were reset, the layout was reset, and it is only showing a single library.

I've got everything mostly back to normal, but I can't figure out how to get it to see all of the other libraries.

I'm on 8.12.0 and everything was fine yesterday evening. So weird.

How do I reestablish the links to all of my libraries?

Thank you!