How to call codebehind LinkButton click event from JavaScript in ASP.Net

Above Links are Not Worked For me

i want to call btnSaveBill Onclick Event When (I Press the Alt+A button) that time the click event of btnSaveclick should fire from script and the code behind code executes.

 In Below Code I want to fire btnSaveBill OnclickEvent Instead Of Alert Message

<script type="text/javascript">
         function KeyPress(e) {
             var evtobj = window.event ? event : e
             //Do action on Alt + A
             if (evtobj.keyCode == 65 && evtobj.altKey)// its checks the alt+A Is press
             {

                 alert(" Alter Alt +A Press");//Msg Display Properly
             }
             //Do action on SHIFT + DELEETE
             if (evtobj.keyCode == 46 && evtobj.shiftKey) {
                 alert("Shift + Delete Pressed");
             }

         }
         document.onkeydown = KeyPress;
     </script>

<asp:LinkButton ID="btnSaveBill" runat="server" CssClass="form-control  btn btn-success btn-block" OnClick="btnSaveBill_Click"><span class="glyphicon glyphicon-save"></span>&nbsp;Save Bill</asp:LinkButton>

protected void btnSaveBill_Click(object sender, EventArgs e)
    {
        SaveBill();
        lblPopMsg.Text = "Bill Saved !!!";
        mpeMessageAlert.Show();
        GenerateBillNumber();

        }

Amol111 says:

<script type="text/javascript">

         function KeyPress(e) {

             var evtobj = window.event ? event : e

             //Do action on Alt + A

             if (evtobj.keyCode == 65 && evtobj.altKey)// its checks the alt+A Is press

             {

 

                 alert(" Alter Alt +A Press");//Msg Display Properly

             }

             //Do action on SHIFT + DELEETE

             if (evtobj.keyCode == 46 && evtobj.shiftKey) {

                 alert("Shift + Delete Pressed");

             }

 

         }

         document.onkeydown = KeyPress;

     </script>

 replace above code with below

<script type="text/javascript">
    function KeyPress(e) {
        var evtobj = window.event ? event : e
        //Do action on Alt + A
        if (evtobj.keyCode == 65 && evtobj.altKey)// its checks the alt+A Is press
        {
            __doPostBack("<%= btnSaveBill.UniqueID %>", "");
        }
        //Do action on SHIFT + DELEETE
        if (evtobj.keyCode == 46 && evtobj.shiftKey) {
            alert("Shift + Delete Pressed");
        }

    }
    document.onkeydown = KeyPress;       
</script>