Cascading Dropdownlist in MVC 5

Question

I am working On asp.net mvc 5 project. I  have select MVC 5 Web Application.There is some inbuilt file like account Controller.so there is inbuilt Register.cshtml file i have modified that file.for registration user can put there country,state.I have taken several way to solve that problem but State Dropdownlist did not populate after select the Country.Please help me...I have used MSSql server and code first migration..If some one do this type of work and help me step by step I'll be gratefull...I have use jquery,azax,json..but Not Working..