How to create searchable bounded ASP dropdownlist

I have a bounded DropDownList in my ASP WebForm.

it's bounded like this:

<div class="form-group">
<asp:DropDownList ID="myDDL" runat="server" CssClass="form control" AutoPostBack="true" DataSourceID="MyDS" DataTextField="EName" DataValueField="A D">asp:DropDownList>
<asp:SqlDataSource ID="MyDS" runat="server" ConnectionString="<%$ ConnectionStrings:Conn %>" SelectCommand="NamesListSP" SelectCommandType="StoredProcedure">asp:SqlDataSource>
div>

i tried to using JQuery (select2.js, dropdownsearchable.js) but nothing working!

any idea please?