Et il va réellement falloir que je mette en système de sauvegarde en place...
And I'm really going to have to put a backup system in place...
Yes I really think you are, but you may be bit late this time.
It is a wise man who has second thoughts first.
There are lots of backup options for SME. I'd implement one or two immediately.
If you have a Prox backup you could restore to another VM and try to recover.
Others may have suggestions on individual file recovery, but the more you use the server, the less chance there is of recovery as the existing blocks get overwritten. So you should shut it down or snapshot it immediately to preserve what you can.