My Scores are getting deleted and are disappearing...They're also somehow getting lost to a previous Version of Musescore...

Hi! If anyone can read this and help me out here, that'll be greatly appreciated!!

So I have this project that I've been working on for an Orchestra performance, but the thing is, it has disappeared twice from my computer. Like, I open up Musescore 4.4.4 (the software) and it's completely gone from my projects menu. I couldn't find it anywhere.
So, I ended up just starting over, and decided to create a new one and for awhile it was doing well with no saving issues. But then one day I opened it up to listen to it, and then I closed it (saving any edits I did too) and then later I opened up the software again, but I couldn't find it on the projects page. I restarted my computer looked again through the software, but alas, still nothing.
So I looked through my files, backup files, "mscz", etc., and I found a project with the same name (I'm pretty sure), so I opened it up, and then it says, "Error, cannot read file. File was saved using a newer version of Musescore; go here to download the latest version of Musescore." Which is weird, because I never saved it in an old Musescore or used it in an old version. I'm pretty sure it was the same project that I was working on earlier, cause the name I think was the same (It was Epic Orchestra piece, or smth like that), and it also said that it had been last modified earlier today. So it must've been the one I've been working on. But I can't open it up, and I'm not sure how to open it up in Musescore 4.4.4, when it should already be in Musescore 4.4.4, because that's the version I wrote the project in.
Anyway, it would be super helpful and appreciated if y'all could help me out here, and figure out a solution to restore my score. I was planning to enter some Orchestra Competitions/performances, so I really need to find the piece. I could just start over, but I had a decent amount of progress, plus, I don't want this to be happening again further down the road with future pieces. =\
So I guess my final questions are, What's causing this? How can I find and restore my piece back so I can continue working on it? And how may I prevent this from happening again?
As for further details, I have my Musescore 4 installed on an external hard-drive, along with my projects. But the thing is, I also have a previous version of Musescore on the laptop I'm using. I'm pretty sure I got rid of it and that it's gone though. Idk for sure. I haven't opened the old one up in awhile.

Thank you for your support,
God bless.