Do you mean he bought the LOAN or the property? If he purchased the loan and is now the lender of record (the person/bank who you owe the money to), he has nothing to do with the first.  We can help with better info:

-Was the property foreclosed on by the lender? If the second mortgage company foreclosed did they notify the first? 

-What do you mean "took over my house"? Were you evicted by the sheriff in your county? No transfer of title is legal until the first mortgage is satisfied & then they are illegally "squatting". Get them out fast if this is the case; CONTACT AN ATTORNEY ASAP!!!

No property ownership can be transferred without legal documents (deed) which you or your representative (POA) must do. Even if a nonvoluntary foreclosure, the lender would get a judgement from a court in order to force the transfer and you would be notified.