Why doesn't a usb port work even after a reset of the bios and a reinstall of all the usb preferences in the device manager?

The physical USB controller might be shot.

If the port is on the front of the base unit, check the able going from the port to the motherboad, reseat the cable at the mother board.

If the port is at the back of the base unit, built onto the motherboard, it may be a hardware fault, may need replacing.