Well, first, if you don't already have an archive, make one. You might also want to publish your files to HTML as well, just to be sure you have copies of everything.
Then, after closing Twine, go to your "C:\Users\(your username)\Documents\Twine" directory and rename the "Stories" folder to something else. Now re-open Twine and hopefully it should show no stories. Then import the archive and see if everything looks correct.
The Twine 2.3.x branch had a major change to the underlying engine (it was switched from Node to Electron), so it's still a bit buggy. Any errors, especially ones you can reproduce, should be added to the Twine issues list (assuming it's not there already). If, after following the above steps, you still have a problem, you might want to ZIP the archive your made earlier and attach it to the issue, assuming you don't mind other people looking at it. That way they might be able to see what went wrong with Twine.
In the meanwhile, you might want to use a separate install of Twine v2.2.1, which is currently a bit more stable. At least until the bugs are worked out.
Hope that helps! :-)