If you have not had your period for four months, the first thing to do is to rule out the possibility of pregnancy, provided that you have had sex. If there is no pregnancy, the following conditions may cause the absence of menstruation: First, menstrual disorders caused by endocrine disorders, such as due to excessive mental stress, cold stimulation, environmental changes, etc., can lead to endocrine disorders and delayed menstruation, or even amenorrhea. Secondly, if there is a history of abortion, it is necessary to exclude that the endometrial lining is damaged due to abortion, which causes adhesion of the uterine cavity and leads to the absence of menstruation. Thirdly, the possibility of pelvic tuberculosis or endometrial tuberculosis should be ruled out, which can also lead to menorrhagia. In addition, tumors and also polycystic ovary syndrome can lead to absence of menstruation. Therefore, the most important thing at this point is to go to the hospital to check the reason for not having a period and then treat it according to the results.