I’ve had this happen more than once, and I’m beginning to think this is a bug.
Once DaVinci has opened, right-click on the project folder and look for something like ‘restore back up’ (it’s 0530, and I’ve barely made it through my first cup of coffee…). It should be fairly obvious from there. That should get you up and running.
I’ve had a project disappear after a 10 month hiatus, and more recently when I hadn’t started up my editor for a couple of months. I lost 3 projects in varying stages of incompleteness. I’m curious if upgrading is the cause. Like you, digging into the project folder just created panic. Once I restored the projects though, everything was there.