Mix 1 tbsp. sodium thiosulfate in a bowl with 1 cup of warm water. This mixture will neutralize the bleach.
Dip a clean cloth into the mixture and blot the jeans until the liquid is absorbed by the denim. Repeat until the stain has disappeared.
Place the jeans in a washing machine and wash them the same way you normally wash your jeans with laundry detergent. Remove the jeans from the washer and set them in a clean, safe place to dry outside, such as a clothesline. The sun will help lighten the color of the jeans surrounding the bleach stain, blending the color of the denim.
Use a clothing dye that matches the color of the denim and apply it to the fabric according to the directions on the label. This can be done by either spot-dyeing the bleached area or by dyeing the entire pair of jeans.