I created a new iMovie 10 project and there was no option to associate it with an event when I created it, which there is when I create one now. I have not updated iMovie since I created the project. After working on the project for a day, I quit iMovie and opened it back up. The project was missing. How do I get it back?
Make sure that it shows nothing over here: under today's date or the title that you have given it. If there is indeed nothing, then try File > Update Projects and Events. If it still doesn't show up, then your only hope is that you have a time machine and that you backed it up.
Just asking, what version of iMovie are you using?
I had the same problem and this fixed it. File ==> Update Projects and Events