Well, based on your screenshots, it looks like you've got your data in the correct location on your file system. But jodybingo makes an important point: "td.db" is a key file in your database, and should something happen to it, your database can get wiped out.
First thing to do is see where the software is looking to find your data. On the Preferences tab, press the Data Stores button. See which Data Store is active, and in which folder it is located. If it is pointing to a different location, point it back to the default location and see if your database comes back.
Second, before you do anything else, take a backup of your database and send it to me. On the Database tab, press the Backup button, make sure "database" is selected, choose a filename you can remember and then attach that to an email to support@thetournamentdirector.net.