You may want to speak with a doctor.

There are a few different things that can cause a missed period for so long and a doctor will be able to treat accordingly.

Depending on what's causing your period to miss you may be put on birthcontrol or suggested changes in lifestyle (diet, amount of exercise, stress level)

It really just depends on what's causeing you to miss.

If you are overweight that could be a reason.. there are other reasons but i dont exactly know what they are lol.. but i lost my period for acouple of yrs til i went to the dr. and they put me on birth control pills to regulate it and it helped. Go see your GYN, or a family Dr.

Overweight, underweight, or possibly some nutritional problems or hormonal imbalances. Either way, you should probably go see a doctor.