Remember Drop down Values after F5 using session/dynamic/sessionStorage

 public ActionResult Index()
        {
List<int> DeptIDs_List= new List<int>();
            List<int> Empids_List= new List<int>();
            List<int> EmpNames_List= new List<int>();
            if (Session["FilterIds"] != null)
            {
              var data = (dynamic)Session["FilterIds"];
              Empids_List= data._Empids;
              EmpNames_List= data._EmpNames;
              DeptIDs_List= data._DeptIDs;
              ViewBag.ids = ((Empids_List != null ? (String.Join(",", Empids_List)) : "") + (EmpNames_List != null ? "|" + (String.Join(",", EmpNames_List)) : "") + ( DeptIDs_List != null ? "|" + (String.Join(",",  DeptIDs_List)) : "")).Trim();
           }
}

 public ActionResult Search( List<int> Empids, List<string> EmpNames, List<int> DeptIDs)
{
Session["FilterIds"] = new
            {
                 _Empids = Empids
                 _EmpNames = EmpNames
                 _DeptIDs = DeptIDs
             };
}


Set Values
sessionStorage.setItem("Empids", $("#ddlEmployeeID").val())

access
sessionStorage.getItem("Empids");