iMovie won't open project

I finished a project yesterday. I went back to the project today to make a few edits, and iMovie no longer shows the project. If I go to my iMovie Projects folder, the project file is there, but there's nothing I can do to make it open in the app. I hadn't made any updates or any other changes to the software or my computer overnight. It hadn't even restarted. Since then, I've tried updating iMovie, but there's no change. Help?