if someone hooks a jumpbox up and it sparks, then there is no power and the only thing that works is the headlights what kind of damage could there potentially be?
One of the main fuses has blown check fuse box under the hood for a blown fuse.
Headlights don't give a hoot about polarity. Power goes in one side of the element and out the other. "Sparks" means it was touched backwards even for a moment? Diode in alternator