Menstruation is the result of the woman NOT getting pregnant that month. Every month the female body prepares for pregnancy by causing the lining of the womb to engorge with blood to provide a safe home for the embryo. If no embryo implants in the womb, the blood is drained from the body (period); and, the womb prepares for the baby again.
Not having a period should not cause you to get sick or die if there is no underlaying reason for the lack of menses. In fact, the female body is programmed to stop all periods at some time in her life because she is no longer of child-bearing age. Menopause (stopping of menses) usually occurs at about 50; but, can occur earlier or later.
It would be wise to go to a doctor to determine if the lack of periods is part of the natural process or if there is something else that is causing them to stop. Better safe than sorry.