Nothing Saving?

For my IB music class I’ve been using musescore 4 to compose a piece for percussion. However; this is now the second time my composition has disappeared. The first time, it said it saved to the cloud. This time, I saved it directly to my computer. When I went to work on it, it wasn’t showing up within musescore so I tried to upload the file I had saved earlier today and got a message saying “this file does not exist or cannot be accessed at the moment”. Does anybody know how to effectively save things??