What does it mean when your period start after going four year of not having a period?

While you should consult a gynecologist, this was what happened to me at first. I had three periods when I was nine, and then none until 11, and then they began steady at 12. It's not uncommon for young girls to have a period, then stop, then start again. Sometimes the body says, "Oh, whoops! We weren't supposed to start doing THAT yet."