Can't find my old projects after updating to 17

Had 16.2.2 before, had issues with audio output switching to other devices randomly so decided to update.
After I update, I find that my local database has no projects. I have not upgraded the database yet.
Should I upgrade to get beck my projects? If not, is there a way to get them back?

[Peter Chamberlain]

If you have not updated the v16 DB v17 wont see the project.

Put v16 back in, check the projects are there, then back up the DB..
Then restore the DB, check the projects are there.

then put v17 in, update the restored DB, Dont change the original v16 DB.