I restrung the big side window day/night shade. When you get it down off the wall you need to lay it on a bed to work on it. It is rocket science and requires patience. I had some damage to the fabric and had to remove a pleat and glue fresh part. I also used painters tape to hold sections together while threading new string though holes. There are websites showing how to restring different size shades with different number of strings as well as instructions and diagrams in repair kits. There are services who will restring shades for you. Here's just one of You Tube How To videos:
http://www.youtube.com/watch?v=0e8vVkuGnRk