Although zippers are one of the great inventions of the 20th century, they are not perfectly reliable. Sooner or later you'll experience the frustration of getting some fabric or lining caught in the teeth of a zipper. Forcing the zipper open usually frees the fabric, but then the zipper may go off track. If the zipper is on a nylon bag, and the rest of the bag is in good condition, try repairing the zipper. With patience and a few tools, it's possible to realign it so it works again.
Move the slider tab of the zipper all the way down to the bottom of the zipper as far as possible. Forcefully spread apart the two tracks of the zipper and pull the slider farther down.
Close the pliers over one of the zipper teeth on the track opposite the slider. The tooth should be as close to the bottom of the zipper as possible. Pull firmly on the pliers to remove the tooth from the zipper fabric.
Repeat the process, removing two or three more teeth each time until there is a piece of fabric cleared of teeth about the length of the slider.
Insert the cleared fabric into the top of the slider in much the same way as the end of a jacket zipper, which opens from both ends, is inserted. Firmly hold the bottom of the cleared track while pulling up on the slider. If the zipper does not align properly, open the zipper all the way and free the track. Remove a few more teeth and insert the cleared fabric again. Repeat this step until the top ends of the zipper are aligned evenly when the zipper is closed.
Keep the zipper in the closed position and thread a sewing needle with thread that matches the colour of the zipper fabric. Make several large tacking stitches in the fabric where the zipper teeth were removed. These stitches should be wide enough to span the width of the closed zipper teeth and act as a new stopper for the bottom of the slider. Take a few reinforcing stitches to tie off the thread. Clip the thread close to the fabric with the scissors.
Open the zipper until the slider stops at the stitches. If necessary, add a few more stitches on top of the others to provide a more secure stopper.
Some zippers have plastic teeth that are all connected to each other. If you notice a long string of plastic unravelling, use wire cutters to separate the teeth you want to remove from the remaining ones. Use embroidery scissors with pointed ends to snip off the fabric more closely.
Work over a large surface where you can collect the removed teeth and dispose of them immediately; they could be a choking hazard for babies and young children.