What Causes Delay In Period?

hi iam 25years 5 3 height and 73 kg weight i have polycystic ovaries and my doc in india suggested me to have modus 10 mg twice for 5 days and then i wll get my periods. i did not get my periods since 3 months and now after having the modus tab i did not get my periods its now 10 days i have st