What happens when your period suddenly stops?
If you are referring to your period not starting after another month, that could mean that you are pregnant. A test might be in order. But there are other factors that can disrupt your normal menstrual cycle. Significant weight loss or excessive exercise for example. Either way, call your doctor if you can't make out a reason or your period stays away for another month!
You should watch out for Polycystic ovary syndrome (PCOS) as well. Small cysts, elevated Testosterone levels, acne, and hair growth can be a sign to look out for.