A zipper that sometimes spontaneously rupture or no longer closes properly. Rub the zipper with a candle and it will be as new.
If a zipper does not want to properly zip, grab a bar of soap and lubricate the zipper. This is now nice and smooth again and again will be easy to zip back and forth. A kind of lubricating oil, but with soap.
If the brake of the zipper does not work anymore [of jeans] take a key ring, and this is done by the hole of the zipper holder [called that?] You do the zip up, and ring do to pants button, after which you buttoning him.