How to show Label value in MasterPage without refreshing the MasterPage using C# in ASP.Net

Hi fareed.fd7,

I have created sample code which fulfill your requirement. You need to assign items count into label inside content page like below.

HTML

Master Page

<div>
    <br />
    <asp:Label ID="lblItems" Text="0" runat="server" /><span class="glyphicon glyphicon-folder-open"></span>
    <br />
    <br />
    <hr />
    <asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
    </asp:ContentPlaceHolder>
</div>

Content Page

HTML

<table>
    <tr>
        <td>
            <asp:Image ID="Image7" ImageUrl="~/Files/Chrysanthemum.jpg" Width="100px" Height="80px"
                runat="server" />
            <br />
            <br />
            <asp:Button ID="btnAdd" CommandArgument="Test1" OnClick="OnAdd" Text="Add Cart" runat="server" />
            <br />
        </td>
        <td>
            <asp:Image ID="Image3" ImageUrl="~/Files/Jellyfish.jpg" Width="100px" Height="80px"
                runat="server" />
            <br />
            <br />
            <asp:Button ID="Button1" CommandArgument="Test2" OnClick="OnAdd" Text="Add Cart"
                runat="server" />
            <br />
        </td>
    </tr>
    <tr>
        <td>
            <asp:Image ID="Image5" ImageUrl="~/Files/Hydrangeas.jpg" Width="100px" Height="80px"
                runat="server" />
            <br />
            <br />
            <asp:Button ID="Button2" CommandArgument="Test13" OnClick="OnAdd" Text="Add Cart"
                runat="server" />
            <br />
        </td>
        <td>
            <asp:Image ID="Image4" ImageUrl="~/Files/Desert.jpg" Width="100px" Height="80px"
                runat="server" />
            <br />
            <br />
            <asp:Button ID="Button3" CommandArgument="Test4" OnClick="OnAdd" Text="Add Cart"
                runat="server" />
            <br />
        </td>
    </tr>
</table>

C#

protected void OnAdd(object sender, EventArgs e)
{
    string Item_id = (((Button)sender).CommandArgument).ToString();

    if (Session["mycart"] != null)
    {
        var productList = (List<string>)Session["mycart"];
        productList.Add(Item_id);
        Session["mycart"] = productList;
        (this.Master.FindControl("lblItems") as Label).Text = (((List<string>)Session["mycart"]).Count).ToString();
        ScriptManager.RegisterStartupScript(this, this.GetType(), "Message", "alert('Item added to cart');", true);
    }

    else
    {
        Session["mycart"] = new List<string> { Item_id };
        (this.Master.FindControl("lblItems") as Label).Text = (((List<string>)Session["mycart"]).Count).ToString();
        ScriptManager.RegisterStartupScript(this, this.GetType(), "Message", "alert('Item added to cart');", true);
    }
}

Screenshot