Missing periods for three months is common and highly treatable. The first step is to rule out pregnancy, followed by identifying the underlying cause, which could be stress, thyroid imbalances, or Polycystic Ovary Syndrome (PCOS). Treatment is tailored specifically to the cause. To restart your cycle, a doctor may prescribe a short course of a progestin hormone (like medroxyprogesterone). For long-term regularisation, combined oral contraceptives or medications like metformin (if related to PCOS) are commonly used. Please consult a gynaecologist for a proper evaluation, which may include simple blood tests and an ultrasound, to determine the best treatment plan for you.