The first thing to do is find the culprit and pull it out. Then rewash all the clothes using a nonchlorine bleach or a cup of white distilled vinegar in addition to your regular laundry detergent. Do this BEFORE you put the clothes in the dryer.
If you have already dried the clothing or the dye transfer is heavy, you will need to take time to soak the clothing before rewashing. Mix a solution of oxygen-based bleach - OxiClean, Clorox 2, Country Save Oxygen Bleach, Seventh Generation Oxygen Bleach - and cool water. Follow the package directions as to how much product per gallon of water. Submerge the stained items and allow them to soak for at least eight hours. Check the clothes and if the dye stains are gone, wash as usual. If they remain, mix a fresh batch of oxygen bleach solution and soak for another eight hours then wash.
This is why clothes should be sorted. Just because something hasn’t faded before doesn’t mean it never will. Sometimes it takes several washings before dyes begin to wash out and cling to the unsuspecting!
Specific questions? Just ask here.