The sour smell that sometimes comes from laundry is often caused by mildew. Mildew forms on laundry when clothes are left in a warm, damp area such as the bottom of a laundry basket or in the washing machine. Mildew can damage fabric and the laundry may need to be washed several times before the odor is removed completely.
Launder the sour-smelling clothes in small loads. Overcrowding the washing machine will keep it from laundering the clothes properly.
Set the washing machine to the hottest water that's safe for the fabric. Always read the care instructions on clothing labels to prevent ruining the material.
Add 1/2 cup of baking soda to your regular laundry detergent. The baking soda will absorb the sour smell. Pour two cups of white vinegar into the washing machine during the rinse cycle.
Wash the clothes again using just your regular laundry detergent.
Place the laundry in the dryer or hang the clothes to dry. Hanging the laundry to dry will allow air to circulate, which will help remove any lingering odors. If using a dryer, put it on the hottest setting the material can withstand. Dry the clothing completely.