The occasional irregular period can be normal. Normal reasons for a missed or irregular period include: Illness such as a flu or bad cold, high stress, travel that messes with your sleep patterns, too much exercise, also if you lose or gain a significant amount of weight.
Here are few tips
Eat well balanced diet.
Do regular exercise like walking for 15-20 minutes.
Try to reduce stress. Try deep breathing exercises.
If you are overweight, lose weight.
Get good night sleep of 7-8hrs.
If your periods are frequently irregular, this may signal a problem. Consult gynaecologist.