Abbi: nobody here wants to see any client have a disappointing experience, as you have had here.
I appreciate so much how you have come back consistently to share updates about your experience. That can be instructive for all of us.
I really hope you will take this as an opportunity to learn more about automated backups. That is really the heart of your problem in this situation, and that is something that has nothing to do with Upwork or any hiring platform.
Your goal should be to have automated backups in place that allow you to retrieve your data and files, so that if disaster strikes, you can recover without having to redo the work and without losing any data. Ideally, you want to have files sequestered into a place that you control, and which a potentially malicious freelancer, employee, etc. can't get to. As a practical matter, you might end up automated backup files that a developer or technical person can indeed get to, but which you periodically sequester to a private location manually.
Not for nothing, and I don't believe your freelancer was hacked, but I was hacked recently and had to notify clients, especially those that had shared passwords with me, and ask them all to change their passwords, etc., to be safe. It does happen. We didn't lose anything though.
When you say you have no protection - you did have protection but you did not use Upwork correctly. You did not get all the credentials delivered back to you, which would be the final deliverable, before you released the final payment and left a review, which would have kept this freelancer from taking the actions he did. Also, when the freelancer tried to manipulate you for 5 star feedback, you should have reported that, and none of this would have happened. I'm not excusing his behavior, but you have to also examine how you failed to use Upwork's protection through the course of this, to the point you got to the end and could no longer avail yourself of Upwork protection.
Hopefully others will learn from your mistakes through this thread.