Restoring project database after version 17 upgrade

I can't restore the project data base file (project.db.####) that was automatically backed-up last time I used the 16 version. I upgraded without doing a manual data back-up because no database appeared. So the 17 was installed and of course no projects appeared. I then installed the 16 version again to try to restore with the project.db file I have, but no matter what folder I put it in, it doesn't appear in the media manager, so that I can load/restore it. Don't know what else to do. What am I doing wrong?
Help!!!