made clunk noise/feeling a few times, then no power 2 drive wont move on 1996 Acura TL

No power is being sent to the drive-wheels, and when you put the car in (P) Park, it still rolls. You can turn on the engine, and it makes a noise - my uncle says the transmission is turning, and engine running, but the differential may possibly be broken, but an Acura specialist says these cars don't generally have differential issues. Could a bolt have came loose and the differential disengaged from Trans?

Asked by for the 1996 Acura TL