I am 17yrs old. i get my periods regularly with a delay in 2-3 days sometimes,now its late by15days,why?.i am not involved in any sexual activity.

Common complaint: Irregular periods are one of the most common problems obgyns treat. If this is one time problem it usually resolves on its own. If this is a recurring problem you should be evaluated. Infections ; hormonal changes can cause spotting. If there is a concern for pregnancy then do a home pregnancy test . There are many options available to help regulate the menstrual cycle. Schedule a visit.