protected void Timer1_Tick(object sender, EventArgs e)
    {
        DateTime NeededByDateTime = (DateTime)ViewState["NeededByDateTime"];
        TimeSpan time1 = new TimeSpan();
        time1 = NeededByDateTime - DateTime.Now;

        if ((time1.Hours <= 0) && (time1.Minutes <= 0) && (time1.Seconds <= 0))
        {

            lblCountdownTicker.Text = "Time Expired!";
        }
       else
        {

        string countDown = string.Format("{0} Days, {1} Hours, {2} Minutes, {3} Seconds until expiration.", time1.Days, time1.Hours, time1.Minutes, time1.Seconds);

        string newCountDown = "<h4 style = 'color: blue' >" + countDown + "</ h4>";

        lblCountdownTicker.Text = newCountDown.ToString();
        }

    }

<asp:ScriptManager ID="ScriptManager1" runat="server" />

        <asp:UpdatePanel ID="UpdatePanel1" Visible="true" runat="server" UpdateMode="Conditional" >
            <ContentTemplate>

                <asp:Label ID="lblCountdownTicker" runat="server"></asp:Label>
                 <asp:Label ID="Label1" runat="server" Text=""></asp:Label>
            </ContentTemplate>
         <Triggers>
            <asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick" />
        </Triggers>
        </asp:UpdatePanel>