Collecting on a stake gone bad

[Reef]

What are my options in terms of collecting a debt from someone I staked who is avoiding me?

I have a written contract in which he agrees to pay me back $X and also keep in contact with me. He has broken the contract. I have his name, know what school he attended last year, address as of a couple months ago (which may or may not be current), various screen shots.

Do I get a collections lawyer? Hire an investigator to find where he lives now?