I had my last period on april 15 and after my periods stopped i took mephrate after 3/4days but my periods has not yet come wht is the reason could u please tell?

You have not provided enough information : have you lost weight? Might you be pregnant? You under a great deal of stress of course being in India right now with Covid, are your periods previously regular? Periods are impacted by many things but most commonly weight loss/anorexia, excessive excercise, pregnancy, and stress. However, if none of those apply to you, you should seek medical attention

Unless it has been 35-40 days since her last period started AND her pregnancy test is negative, there is no indication to take *any* progesterone at all.