MuseScore crashed and I can't open the score I was working on

I was working on a new score for an hour or so, and then the whole application just shut down unprompted. I didn't have a chance to save anything. This was before I installed 4.5 by the way. When I right click the application and click "Show Recents", all of my score files pop up, and I can only open a couple of them. There is one called "not_uploaded_0.mscz" that I think might be the one I was working on. I cannot open it. Someone help please!! I've already reset the application to factory settings. That fixed a bug I was having a while ago but this one has not been resolved.