Hormonal imbalance, stress, certain medications as contraceptives, polycystic ovarian syndrome, eating disorders, vigorous exercise and thyroid disorders, could also cause
delayed period. You can do a urine pregnancy test, and if it is negative consult a gynecologist.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor.