Agitate the brakes physically by applying and releasing the brake a number of times. Or shift alternately into drive and reverse to lurch the vehicle back and forth. Or bounce the car up and down near the seized wheel.
Support the car securely on a jackstand. Remove the wheel to gain access to the seized brake. Take care not to damage any parts as you tap the brake assembly with a hammer to free the pads from the disc or drum.
Test the parking brake cable to see if it is broken or stuck. Release the cable from the rear passenger side brake caliper and try to free up the cable movement with a penetrating rust remover, or if necessary, replace the cable.
Maneuver two screwdrivers through the access port on the drum brake backing plate to loosen the tension adjuster screw. Remove the drum and replace the brake cable, brake shoes and return spring, as necessary. Refer to your vehicle service manual to find the detailed procedures for your specific model. Reassemble the brakes, lower the jack, and test the brakes.