Try this? (it worked for me after I saw that all my projects disappeared, aka, the database got disconnected)
On the startup project window, in the left column, click on the little person with 3 bars to THEIR left. Try switching between "admin", "guest", etc.
I THINK MY ISSUE was that, in the past, I set up my database under "guest" instead of "admin". I started trying to fix the missing database issue with only a focus on "admin". Curiosity had me randomly take a look inside the "guest" folder in my Resolve Disk Database, and tada! "THERE THEY ARE!!!" moment.
I know these questions are old, and my answer late, but ya know, maybe my comment will help someone anyway somehow