You should be able to restore your clothes to white (and not damage the fibres of the fabric) by soaking them them in lukewarm water and color safe or oxygen bleach for 24 hours, then rinse them with vinegar and water. Use one tablespoon of vinegar to one quart of water. After treating them overnight, wash them in hot water with chlorine bleach added. This should refresh them to their original white state. If possible, dry them in the sun.