Your menstrual cycle is under hormonal control. The ovary usually releases one egg (ovulation) each month, and about two weeks after, the uterine lining sheds, resulting in menstruation. If the egg is fertilized, it is implanted into the uterus and menstruation does not occur. However, if ovulation does not occur regularly, the body does not send signals to the uterus to regulate menstruation. Stress, jet lag, lack of sleep and too much exercise can disrupt your hormonal balance and cause a change in your usual menstrual cycle....Consult nearest gynecologists they will do the needful.

HELLO MADAM, KINDLY WAIT FOR NATURE TO TAKE ITS OWN COURSE, IT MAY BE ANOVULATORY CYCLE IT MAY COME A BIT LATE WAIT AND WATCH , RESULTS WILL FOLLOW GOOD LUCK BYE

Hello. I understand your problem. Few clarifications are needed first. 4-5 days delay of period is not alarming, you can wait few more days, as the delay may be natural. If you are sexually active, do a urine pregnancy test to rule out any pregnancy. If you are not, then this delay in period may be due to few reasons such as thyroid abnormality, hormonal imbalance or PCOD (polycystic ovarian disease). If your period doesn't start in next few days, do serum TSH, Free T4, afSH, LH levels and an Ultrasound of whole abdomen. Follow up with me with the reports. Hope this helps.