Alfer my thrid chrild I took inpant, since then I ve not seen my pirod. Why?

Need more info. How long ago did you have your third child? Are you breast feeding? What do you mean by "inpant"? Do you mean implanon? Do you have an iud?
Depends. The "nexplanon" device/"implant" (a more image friendly Implanon product) is also available.