If I sold my house with closing cost and everything included. The gentleman assumed the payments. Never changed them into his name and has on several occasions, he has missed payments on the loan. It has damaged my credit. What can I do to save what credit I have left?

This is way too fishy. The moment you sold your house you should have paid off and closed out your mortgage. Why didn't you? Since you are no longer the owner, it is deceptive (illegal?) to pretend to the bank that you are still the owner. Has the new owner been registered on the deed to the property?

Yes, sound like one of those "scam" sales where they claim to save your home and take over your mortgage??

I would take all my paper work to a real estate attorney and have them review it