Check the existing zipper slider:

If the slider is still in place, move to the next step.

If the slider is missing, and there are missing teeth on the box side of the zipper line, use any voided area on the zipper line to place a new slider onto the track. Then move on to the next step.

If the slider is missing, and no teeth are missing or damaged on the box side of the zipper line, follow the Plastic Tooth Zipper Slider Replacement guide. Then move on to the next step.