Hi.im Ashmy I'm 21 years old.its been 4 months that I missed my periods.i don't know why..I'm not pr

4 months is already a while. Are you underweight or overweight? These are most common causes. Have you had regular cycles beforehand? After 6 months one would check a few hormons and have a look by ultrasound. You can always try Agnus castus (i.e. "Agnucaston"). (of course always assumed that you´re really not pregnant.)