Hello there, thanks for writing in. Delayed periods is because of arrested ovulation. Menstruation always happens 2 weeks following ovulation if the egg is not fertilised by sperm. Ovulation can be halted at times of excessive stress, excessive physical exertion or poor nutrition. Ovulation can be infrequent and irregular in polycystic ovarian syndrome too where there is resistance to the action of insulin ( hormone that controls blood sugar ) and that in turn leading to excess male hormones and to arrested ovulation. If you have had previous regular cycles, then this random event of ovulation arrest is not worrisome. You may take tab.medroxy progesterone acetate 10 mg for 10 days to induce periods. You may expect your periods in 2 to 7 days once you stop your medication. I must warn you that this periods can be slightly heavy and painful and you can take ibuprofen or mefenamic acid to reduce it. Hope this information helped you. Take care.