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Stress, lifestyle changes, changes in diet, sleep or exercise levels, hormonal imbalances, infections, pregnancy, etc can cause delay in periods. If you do not get your periods within 10 days of expected period dates or if you develop any new symptoms, visit your doctor/gynecologist at the earliest for further evaluation and tests to look for the underlying cause. Drink plenty of water. Take adequate rest. Maintain healthy diet. Treatment as needed (based on examination and investigations results) would be started to help you get back periods.
Take care.