I Have Few Cases Of Women Coming To The Clinic

I have few cases of women coming to the clinic with complaints of ammenorhoea for 3 months .SCAN has been done with no intruterine pregnancy noted. I have been advising them about the side effects of Depo Provera that they were using before...I have given them Microgynon pills which will help them regulate their menstruation..Can you please explain to me how effective is Microgynon pills will help menstruations resumed to normal or how does it work???