I was editing wedding photos in LR Classic. I edited a few in a plugin (Topaz denoise), and that seemed to work fine. I had to stop and upgrade Topaz Denoise, because I had not paid for it yet. When I went back into LR Classic all my 2020 folders were gone from the catalog I was working in. I've spent the last 3 or so hours trying to figure this out. I only used one catalog. Now I am up to five because it makes me upgrade, and it will create another catalog. But my older folders are still not in any of them. I know they are still on my hard drive, but I am wanting the folder of edits that I was working on back! It was a wedding and I have a lot of edits finished but weren't exported yet! I don't want to start over. Can anyone help?
Sounds like you opened an older catalog at some point without realising it, perhaps from a backup. If you do make backups, then that is the way to get back the latest one if you can't find it any other way.