in the absence of details, one cannot suggest the method of recovery.

sir, it would depend upon the terms of contract, where it was executed and/or accepted. It would also depend whether or not there is any arbitration clause. Before you take any action against the other side in US, you have to check if usa party has not filed bankruptcy in US.

There are 50 states in USA and each state has it own laws for recovery. Your debtors is in which state ?. What kind of agreement you had with him for him to pay you the money. What kind of business activity(ies ) you had with your debtor. Please clarify to get legal opinion.