If your period is usually regular and you suddenly stop menstruating, and if you have a history of sexual intercourse and are not using contraception, you should first rule out the possibility of pregnancy. Generally, you can collect morning urine for an early pregnancy test, and if two red lines appear, pregnancy is indicated. If there is one red line, you are not pregnant. If you are not pregnant, you can take progesterone orally to induce menstruation. Take two capsules once a day for three days, and you will get your period 3-7 days after you stop taking it. Since progesterone is taken orally to induce menstruation, the volume of menstruation will be slightly more than the previous volume of menstruation, do not be nervous. Also, since progesterone may cause dizziness after taking it orally, make sure to take it orally before going to bed to avoid dizziness.