Lost work in Movie Maker

I was working on a project in Movie Maker. This is the 3rd day of editing a film. I had saved the work from the other 2 days. I was nearing the end of working today when all of a sudden the film segments on the right went white one by one with exclamation points in them. I double clicked on one and a message came up that a file with a slightly different name than the one I was working on had been corrupted and needed to be deleted before I could go on. I clicked no, but nothing happened. Finally, since I couldn't work on it, I clicked yes. My whole film disappeared. The file name still shows up in the list of files, but there's nothing there. All of the previous work I had saved is gone, too. How can I find and recover this. It's been many hours of work. Thanks.