How can I unstick a zipper on a backpack?

To unstick a zipper on a backpack, try applying a lubricant like soap, candle wax, or a graphite pencil to the teeth of the zipper. Gently work the zipper back and forth to help loosen it. If that doesn't work, you can also try using a pair of pliers to carefully pull the zipper apart. Be cautious not to force the zipper, as this could damage it further.