My son just purchased a 1999 Ford Escort with 142,000 miles for $1,000. It is a 5 spd manual transmission. He’s driven the car for a week.
Here is the problem. When we put the car in gear (any gear),and release the clutch. It doesn’t move. It hear a whirling noise like something is turning. Is this the clutch or transmission?
99% probability that it is the clutch.
I am going to assume the car did run OK and now it does not move at all. Is that true?
If so It could be either, I would guess the clutch is far more likely of the two.
yes, the car was running fine. He drove it to school in the morning, and when he went to drive home. It wouldn’t move in any gear.
They still don’t put sawdust in the transmissions do they? Is it too late to return thee car?
Somehow, I think that a $1,000 car was likely sold as-is.
I hope for the OP’s sake that I am wrong, but the likelihood is that the car was sold w/o a warranty.
Sold as-is from a private seller 
It would help to know if there was a burnt smell associated with the problem. When clutches go, it’s usually noticed as a gradually increased slipping and a smell of burnt friction material.
One possibility is that an axle shaft has come out.