Hi Jon,
It is funny that you say this, I wrote a documentation on how to fix this due to me having the same issue! (Database got wiped).
Please use this guide for reference:
Long story short, it’s a case of rebuilding the database with the folder entries.
The issue you may find is getting the folders re-assigned to the correct people so in my case I just assigned them all to the admin and then re-distributed the files.
You will need to re-create the user accounts this way, but if you have a backup of the database, just use that and then remove all of the entries for the folders and re-add them using the entires from the forum.
Any questions, please let me know!
Kind regards,
Mitch