there can be many causes for amenorrhea
here.Its necessary to rule out all other causes for this like hormonal
problems,and any pathology that may be causing this.You will need to see a doctor to rule out some conditions like cyst,hypothyroidism
,prolactenemia.If all is normal then you will need medicines for withdrawal bleeding.Another important cause that may stop your periods is stress
so i hope that is not the case.I suggest you see a gynaecologist for this.