82 Ford Fairmont wont charge

My 1982 Ford Fairmont wouldn’t start in Walmart after it had been driven for about an hour. I was able to get the car jumped and limped it home. I had been in Walmart for quite a while and had figured that I had left the car in accessory mode and killed the battery. When I got the car home, I let it fun for about 30 minutes. The lights seemed dim, but I was hoping for the best. The car wouldn’t start the next day, so I bought a battery. It was almost midnight, and I know better but I wanted to see if I would be able to drive the car to work the next day, so I put it in-backwards. The solenoid started smoking and I heard a ‘pop’. I put the battery in the right way, but now the alternator light came on.

My dad replaced the alternator and the voltage regulator, but the car is not charging. My dad is a very experienced and talented mechanic but he is stumped.

Any and all helpful suggestions are welcome.

starter?

I would be surprised if this car did not have a fusible link in the positive battery cable.
In view of how cheap battery cables are, I would suggest installing a new one and seeing whether function is restored.

It wasn’t the solenoid that smoked it was one or more of the fusible links that use the solenoid stud as a junction. If the key was in the OFF position the fusible link to the alternator may be the only one burned.

My dad is a very experienced and talented mechanic but he is stumped.

This should be quite simple. Have your dad get out his old wiring diagrams and trace all the fusible links and repair as needed.