It seems like the simplest of problems, but a stiff zipper can really ruin your day. Most people don't give zippers a second thought until they stop working correctly. You may avoid wearing that favorite outfit when the zipper becomes stiff. If the problem persists, you might even throw the garment out altogether. Before you do anything rash, you can try to loosen the zipper yourself. Chances are, you've already got something around the house that will cure your wardrobe headaches.
Lubricate the zipper by rubbing lip balm over the teeth. You can also use a bar of soap for the same effect.
Rub the lead of a pencil over the problem area. Zip and unzip until the action becomes smooth.
Soften a wax candle by applying heat with a hair dryer. Rub the candle over the zipper teeth to provide lubrication. Avoid over-coating; you'll only need a little wax.
Apply a coating of clear silicone spray to the zipper. Work the zipper up and down to spread the silicone over the teeth.
If your zipper becomes stuck, check to make sure there are no strings or fabric caught in the pull.
Don't use Vaseline or other petroleum-based products on your zippers.