Well, in europe you can enter a legal contract with 16+ years if your parents give their conscent to it.
In any case! Thanks for all the advice, I decided to go the "ask nicely" way. And whaddayaknow, It worked!
At least I got the most important files back. So I could finish for the deadline.
I didn't sleep very well last night, but I will sleep like in heaven tonight.
..
Though, I really doubt I'll be working with that guy again anytime... in my life.