HOW to Changed Writing English To Urdu Textbox html Javascript

JS file

 <script src='<%=ResolveUrl("~/Scripts/plugins/Urdutextbox/urdutextbox.js") %>' type="text/javascript"></script>
    <script> window.onload = myOnload;

        function myOnload(evt) {
            MakeTextBoxUrduEnabled(txtStudentNameUrdu);//enable Urdu in html text box
            MakeTextBoxUrduEnabled(txtFatherNameUrdu);//enable Urdu in html text area
        }</script>
</asp:Content>

 <label for="inputStudentName" class="col-sm-1 control-label input-sm">Student Name (Urdu)</label>
     <div class="col-sm-2">
        <asp:TextBox ID="txtStudentNameUrdu" dir="rtl" runat="server" class="form-control input-sm" ClientIDMode="Static" placeholder="طالب کا نام" MaxLength="60"></asp:TextBox>
      
  </div>
    <label for="inputStudentName" class="col-sm-1 control-label input-sm">Father Name  (Urdu)</label>
  <div class="col-sm-2">
  <asp:TextBox ID="txtFatherNameUrdu" dir="rtl" runat="server" class="form-control input-sm" ClientIDMode="Static" placeholder="باپ کا نام" MaxLength="60"></asp:TextBox>
  </div>