Thanks, I got the file. Unfortunately it confirms my suspicion: it is an empty database file; it contains only the schema but no data. Even when Tropy creates a new project initially it would contain some data (that’s why there is an error when trying to open the project now) so my working theory as to what happened is this:
After Tropy was re-installed, it had no ‘memory’ of the original project, so at start-up it would have opened the project wizard. Now my guess is that your colleague created a new project and changed the location to that of the original file; Tropy would have prompted whether or not to overwrite the file at this point; when confirmed the project would have been overwritten by a new one and then, during the project initialisation, there must have been an error that caused the project creation to abort before the project was finished (after the schema but be before the initial data was written).
I’m really sorry that there is no way to recover any data from this file, because it has been overwritten. I hope you still have a backup copy?