The zipper on my bag stopped working about a year ago. I had been trying to use it anyway but things kept falling out. I recently learned that hand stitching isn't that hard, so I went out and got a new zipper. Here's the old zipper for reference
Not OP, and I suck at hand stitching, but I usually use the thickest stuff I have on hand to account for the reduced stitch count. Also because I like how it looks.