Things You'll Need
Instructions
Repairing the Zipper
Take apart the old zipper. Start by removing the metal stop at the bottom of the zipper with the pliers. The stop is similar to a staple, so a flathead screwdriver could help as well. With the stop removed, pull the slider to the bottom of the zipper. Bring it as far down as you can without removing.
Realign the teeth of the zipper. Misaligned zipper teeth could cause the zipper to catch or pull apart when it should be closed. Aligning the zipper may take practice, but continue until both sides are straight. If you need to put the slider back on, do so before you get the teeth aligned.
Pull the slider up halfway along the zipper. Go slowly, and carefully inspect the zipper to make sure all the teeth are interlocking correctly. If you have any problems, try to realign the teeth again. Do this until the slider moves smoothly along the zipper.
Close off the bottom of the zipper. If the stop you removed is still in good shape, reinsert it along the bottom of the zipper. If the stop is too damaged to be used, use your needle and thread to make multiple, tight stitches around the zipper to create a new "stop." Make at least six stitches around the zipper before you tie off and trim the excess thread, but use as many stitches as necessary to keep the zipper secure.
Test the zipper. If it works successfully you are done. If you are still having snags, you can repeat the process you just attempted or replace the zipper in its entirety.
Replacing the Zipper
Remove the old zipper using the seam ripper.
Align the new zipper and hold it in place with pins.
Close the zipper to make sure the pillow will close properly, and open it again to give you access to sew it in place.
Sew with either a needle and thread or a sewing machine, whichever you feel more comfortable with, until both sides of the zipper are firmly secured.