Slide the zipper down to its base or the starting point of the zipper track.

Avoid forcing the zipper past the point where it's stuck, as this may make restoring full functionality more challenging.

Pull both sides of the fabric sides away from the zipper track.

This will ensure no fabric is near the track. Pulling the fabric away may restore functionality if it has gotten stuck in the track. You may need a friend for this so you can work on the zipper in the next step.