I don't have my period 4 months ago. what should i do?

First: do a pregnancy test. If you are sexually active, that is the first consideration. If the test is positive, you need to see a doctor for prenatal care. If it's negative, you need to see a doctor to sort out why you aren't having periods. Bottom line, see a doctor.

Worthwhile seeing MD: There are a number of reasons why a period may not come on. One of course is pregnancy, in which case an over-the-counter pregnancy test could help. Stress and poor nutrition can interfere with the normal menstrual cycle. Various hormonal problems including thyroid disease can contribute. It is best to get seen to figure out what is causing the problem in your specific case.