To fix a zipper, several common methods can be tried depending on the issue:

• If the zipper slider won't close the teeth properly because it has loosened, use pliers to gently pinch the top and bottom plates of the slider closer together until it properly engages the teeth again. Be careful not to press too hard to avoid breaking the slider.
• If the zipper pull has come off, remove the stops at the top of the zipper, put the slider back on the teeth from the bottom, and then replace the stops.
• For a stuck zipper, lubricate the teeth with a graphite pencil, petroleum jelly, bar soap, or olive oil and then gently work the zipper up and down.
• If the zipper teeth are misaligned or separated, carefully realign or replace the damaged teeth with pliers.
• If the zipper pull is broken, it can be replaced with a new one from a similar zipper or bought online.
• Tools commonly needed include pliers, a flathead screwdriver, and optionally a lubricant.
• Small tears on the zipper tape or missing stoppers can often be fixed with some basic sewing.

These fixes can extend the life of the zipper without having to replace the entire zipper or garment.