Thanks for the information. This problem just started about week ago. Since I access Microsoft Jigsaw my desktop computer, I don't have an app. It's a downloaded program. I have uninstalled the program, downloaded and installed a new version, but the results were the same. The "Classic Jigsaw" screen has been changed and it only gives me access to two of my previously downloaded collections. The last collection that I downloaded about a month ago is no longer visible. I was working on the next to last puzzle in the collection, but I can't access it anymore.
As you suggested, I looked at the downloadable collections and there were many collections there that I had previously downloaded, even the one I downloaded last month. My "Classic Jigsaw" screen must be different than your, as I don't have a manage disk space option. I looked at the jigsaw jam and daily challenges screens, but there was no access to any of my collections. My points displayed at the upper right look correct.
Since the "Classic Jigsaw" screen has been changed, I suspect that is the problem. There used to be a scroll bar at the bottom of the screen that allowed access to all the downloaded collections. The new screen does not have the scroll bar. The screen now has "My Custom Puzzles" on the right with no way to get more than the two collections that are shown.