I had this as well a couple years back. Your period can dissapear for many reasons such as stress, weight gain or loss, and even conditions such as depression can cause a vanishing act with your period.
In my case, I had a functional cyst that was holding up my periods. My advice would be to go to your gynocologist and request an ultrasound, have your blood and thyroid tested and get a through pelvic exam.
Best of luck!