One part Dawn dishwashing liquid mixed with two parts HYDROGEN PEROXIDE. Add baking soda for scrubbing help. Use laundry brush to work into the stain. Supposed to actually take yellow armpit stains out of white shirts!
How to get your dirty whites clean again HOT HOT water, 1 cap of laundry detergent, 1 cup powdered dish washer detergent, 1 cup bleach, cup borax. Rewash it once to put softener in it. If you omit the bleach it works great to get stains out of colors too.