You have not indicated your age. Did, you get your first ever periods? If no then wait until puberty. Puberty in girls is achieved after 11 years depending upon environment. In some areas of the world, it can be early and in some as late as 16. If you are already getting periods and now no periods then cause should be investigated. There are many causes of absence of periods, some of them are physiological while other pathological. Treatment depends upon underlying cause. Following are some causes of absence of periods in women after getting their first periods.
1. Thyroid problems
2. Tumors in pituitary gland
3. Excessive exercise
4. Hormonal imbalance
5. Stress
6. Under weight
7. Chronic illness
8. Pregnancy
9. Breast feeding
10. Use of hormonal birth control methods
11. Certain medicines like antidepressants, oral corticosteroids
So, you should visit a doctor.
1. Thyroid problems
2. Tumors in pituitary gland
3. Excessive exercise
4. Hormonal imbalance
5. Stress
6. Under weight
7. Chronic illness
8. Pregnancy
9. Breast feeding
10. Use of hormonal birth control methods
11. Certain medicines like antidepressants, oral corticosteroids
So, you should visit a doctor.