Show Hide DIV based on condition from code behind using C# in ASP.Net

Hi nedash,

Refer below code.

HTML

<asp:UpdatePanel ID="UpdatePanel13" runat="server">
    <ContentTemplate>
        <div id="DaddMainM" runat="server">
            <asp:Label ID="Lbltell" runat="server" CssClass="tellC1M">12345</asp:Label>
            <asp:Label ID="Lblmobile" runat="server" CssClass="tellC3M">4568</asp:Label>
            <asp:Label ID="Lblemail" runat="server" CssClass="tellC6M"></asp:Label>
            <asp:Label ID="Lbladd" runat="server" CssClass="tellC9M"></asp:Label>
        </div>
    </ContentTemplate>
</asp:UpdatePanel>
<asp:UpdatePanel ID="UpdatePanel9" runat="server">
    <ContentTemplate>
        <div id="DaddMain2M">
            <asp:TextBox ID="TxtnameS" runat="server" CssClass="txtnameCM"></asp:TextBox>
            <div id="DaddMain3M">
                <asp:TextBox ID="TxtmobileS" runat="server" CssClass="txtmobCM"></asp:TextBox>
                <asp:TextBox ID="Texthome" runat="server" CssClass="txthomeCM"></asp:TextBox>
            </div>
        </div>
        <div id="DaddMain2M1">
            <asp:TextBox ID="Txttopic" runat="server" CssClass="txtEmailTM"></asp:TextBox>
            <asp:TextBox ID="TxtdesS" runat="server" CssClass="txtdesCoM" TextMode="MultiLine" ForeColor="#4e4e4e" onblur="WaterMark(this, event,'متن پیام خود را به صورت مختصر تایپ نمایید');" onfocus="WaterMark(this, event,'متن پیام خود را به صورت مختصر تایپ نمایید');" Text="متن پیام خود را به صورت مختصر تایپ نمایید" onpaste="return false;"></asp:TextBox>
        </div>
    </ContentTemplate>
</asp:UpdatePanel>
<div id="DnameC6M" runat="server">
    <asp:UpdatePanel ID="UpdatePanel5" runat="server">
        <ContentTemplate>
            <asp:ImageButton ID="Imgsend" runat="server" ImageUrl="~/Image/main/sendifoC.png" CssClass="imgSeneMeM" OnClick="ImgsendMessage_Click"></asp:ImageButton>
        </ContentTemplate>
    </asp:UpdatePanel>
    <asp:UpdatePanel ID="UpdatePanel10" runat="server">
        <ContentTemplate>
            <div id="cap3DM">
                <asp:Label ID="lblStopSpamS" runat="server" CssClass="CpassM"></asp:Label>
                <asp:TextBox ID="txtStopSpamS" runat="server" CssClass="CtxtM"></asp:TextBox>
            </div>
        </ContentTemplate>
    </asp:UpdatePanel>
</div>
<script type="text/javascript">
    function HideDaddMainM() {
        $('#DaddMainM').hide();
    }

    var prm = Sys.WebForms.PageRequestManager.getInstance();
    if (prm != null) {
        prm.add_endRequest(function (sender, e) {
            if (sender._postBackSettings.panelsToUpdate != null) {
                HideDaddMainM();
            }
        });
    };
</script>

Code

protected void ImgsendMessage_Click(object sender, ImageClickEventArgs e)
{
    if (Txttopic.Text == "" || TxtnameS.Text == "" || TxtdesS.Text == "" || TxtmobileS.Text == "" || Texthome.Text == "")
    {
        messageC.Visible = true;
        captchaES.Visible = false;
        ClientScript.RegisterStartupScript(this.GetType(), "Popup", "HideDaddMainM();", true);
    }
    else
    {
        messageC.Visible = false;
        DsendCS.Visible = true;
        captchaES.Visible = false;
    }
}