That is the question, accidentaly saved empty file into a good file. It was an adobe illustrator project.
Is there any way to get it back?
I'm on Os X.
On Windows, you could use a program like Recuva, which is free. On Mac, the only alternative I know of that works decently well, and is still affordable, costs money, and that's DiskWarrior.
As far as I know (which, admittedly, about Mac's is not much beyond standard IT), there's no free alternatives, or built-in OS functions.