I've had a few requests to create tutorials for basic sewing repairs. The most frequent request is about how to replace a zipper. I will admit upfront that I am not fantastically good at this. My zipper replacements have been adequate (mostly), but not tremendously pretty. It is one of those things where taking the time pays off in aesthetics, and if you notice how many of my tutorials are based around doing something quick quick, you'll know that time is not where my wealth is.
Zipper replacement is extremely intimidating to us novice stitchers. I would of never even tried it except that the sewing test I took as a prerequist to my brief stint as an actual real live professional seamstress in training (no, not that kind, thank you pratchett readers), was to replace a jean's zipper (talk about being in over one's head). I did learn what how the pros do it (and passed the test too). Let me tell you, it is not difficult. But it does take time. And a seam ripper.
Sorry, no whizzy photos in bad lighting for this one. You've seen zippers (hint: look down). Are you ready to learn professional seamstress craft secrets of zipper replacement?
Okay: First, use a seam ripper (or a razor blade) to remove the stitching holding on the broken zipper. As you are removing the stitches, take note of how the zipper was sewn in (or take a picture with a camera if there is something particularly interesting or odd about it).
Second, sew in the replacement zipper in the exact same location as the broke one using the holes from the removed thread as a guide. That's it.
There really is no mystic to replacing zippers, it's mostly just a puzzle - fitting the new piece in so that all the edges align. Time, and a seam ripper, are your greatest assets. And maybe a glass of wine.