WHAT KIND ATTORNEY OR AGENCEY CAN HELP ME. HAVE SOME ADVICE?

I LEND A FRIEND $15,000.00 TO OPEN A NIGHT CLUB A YEAR AG. HAVE A CONTRACT THAT HIM AND HIS WIFE SIGNED. SEND THEM SEVERAL LETTERS AND CALLED THEM HUNDREDS OF TIMES. HAVE GONE TO THERE HOUSE AND THEY NO LONGER OPEN OR ANSWER MY CALLS. I LEND THIS MONEY IN GOOD FAITH AND WOULD HAVE NEVER THOUGHT THEY WOULD DO SOMETHING LIKE THIS TO ME. THE LAST PHONE CALL WITH THEM, THEY TOLD ME THAT THEY WERE SELLING SOME PROPERTY OUT OF STATE SO THAT THEY COULD PAY ME BACK. THAT WAS IN JUNE HAVE NOT HEARD FROM THEM SINCE. THIS SITUATION HAS MADE ME LOOK AT EVERYTHING DIFFERENTLY NOW AND I CAN UNDERSTAND WHY THEY WOULD DO SOMETHING LIKE THIS TO ME. NOW I AM VERY ANGRY AND I WANT THEM TO PAY. BUT I CAN'T SEEM TO FIND THE RIGHT COLLECTION AGENCY OR ATTORNEY I NEED. SO MY ? IS WHAT KIND OF ATTORNEY/AGENCY I NEED?