Text the person and ask your money. If he says 'no, i wont give your money' in the text, that will serve as a legal document to prosecute him. Email will also do.  
If the person admits that he has taken money and will pay later, you can't do anything legally. You have to show the evidence that the person has no intention to pay back. 
Go to district attorney's office and file a case against him. You have to mention his address too.

I think the person is he. If she, read accordingly. People sometimes don't appreciate the help you do. They become so big in a few months that they forget they might need people in future. If it was Nepal, that bastard would not have that much courage to deny paying back. But, unfortunately, here things are different. Anyway, hope you get your money back.