I'm' a us citizen his visa expired 3 months ago. He decided not to be married anymore and went back to his country and left the divorce in my hands we have no property together. No children, no argument.. What is the first step to take to get a divorce quick as possible when he is not available to participate?

It is not going to be as easy and it will cost a lot more if he can not be reached to mail divorce papers to and have him sign them.

But you will need to hire an attorney, an attempt to serve him will have to be made, according to court rules.