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?
iMovie '11, OS X Mountain Lion (10.8.5)