Hi safzal.it,

Check this example. Now please take its reference and correct your code.

For creating zip file i have refered below article.

Download multiple files as Zip Archive File in ASP.Net using C# and VB.Net

Database

I have made use of the following table with the schema as follows.

You can download the database table SQL by clicking the download link below.

Download SQL file

HTML

<asp:FileUpload ID="FileUpload1" runat="server" />
<asp:Button ID="btnUpload" runat="server" Text="Upload" OnClick="Upload" />
<hr />
<asp:GridView ID="gvFiles" runat="server" AutoGenerateColumns="false">
    <Columns>
        <asp:TemplateField>
            <ItemTemplate>
                <asp:CheckBox ID="chkSelect" runat="server" />
                <asp:HiddenField ID="hfId" runat="server" Value='<%#Eval("id") %>' />
            </ItemTemplate>
        </asp:TemplateField>
        <asp:BoundField DataField="Name" HeaderText="File Name" />
    </Columns>
</asp:GridView>
<br />
<br />
<asp:Button ID="Button1" Text="Download" runat="server" OnClick="Download" />

Namespaces

C#

using System.Configuration;
using System.Data.SqlClient;
using System.IO;
using System.Web.UI.WebControls;
using Ionic.Zip;

VB.Net

Imports System.Configuration
Imports System.Data.SqlClient
Imports System.IO
Imports System.Web.UI.WebControls
Imports Ionic.Zip

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
        using (SqlConnection con = new SqlConnection(constr))
        {
            using (SqlCommand cmd = new SqlCommand())
            {
                cmd.CommandText = "select Id,Name from tblFiles";
                cmd.Connection = con;
                con.Open();
                gvFiles.DataSource = cmd.ExecuteReader();
                gvFiles.DataBind();
                con.Close();
            }
        }
    }
}

protected void Upload(object sender, EventArgs e)
{
    string filename = Path.GetFileName(FileUpload1.PostedFile.FileName);
    string contentType = FileUpload1.PostedFile.ContentType;
    using (Stream fs = FileUpload1.PostedFile.InputStream)
    {
        using (BinaryReader br = new BinaryReader(fs))
        {
            byte[] bytes = br.ReadBytes((Int32)fs.Length);
            string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
            using (SqlConnection con = new SqlConnection(constr))
            {
                string query = "INSERT INTO tblFiles VALUES (@Name, @ContentType, @Data)";
                using (SqlCommand cmd = new SqlCommand(query))
                {
                    cmd.Connection = con;
                    cmd.Parameters.AddWithValue("@Name", filename);
                    cmd.Parameters.AddWithValue("@ContentType", contentType);
                    cmd.Parameters.AddWithValue("@Data", bytes);
                    con.Open();
                    cmd.ExecuteNonQuery();
                    con.Close();
                }
            }
        }
    }
    Response.Redirect(Request.Url.AbsoluteUri);
}

protected void Download(object sender, EventArgs e)
{
    using (ZipFile zip = new ZipFile())
    {
        zip.AlternateEncodingUsage = ZipOption.AsNecessary;
        foreach (GridViewRow row in gvFiles.Rows)
        {
            if ((row.FindControl("chkSelect") as CheckBox).Checked)
            {
                string id = (row.FindControl("hfId") as HiddenField).Value;
                byte[] bytes = GetBinaryData(id);
                zip.AddEntry(row.Cells[1].Text.Trim(), bytes);
            }
        }

        Response.Clear();
        Response.BufferOutput = false;
        string zipName = String.Format("Zip_{0}.zip", DateTime.Now.ToString("yyyy-MMM-dd-HHmmss"));
        Response.ContentType = "application/zip";
        Response.AddHeader("content-disposition", "attachment; filename=" + zipName);
        zip.Save(Response.OutputStream);
        Response.End();
    }
}

private byte[] GetBinaryData(string id)
{
    byte[] bytes;
    string conString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    string query = "SELECT Data FROM tblFiles WHERE id = @Id";
    SqlCommand cmd = new SqlCommand(query);
    using (SqlConnection con = new SqlConnection(conString))
    {
        cmd.Parameters.AddWithValue("@Id", id);
        cmd.Connection = con;
        con.Open();
        bytes = (byte[])cmd.ExecuteScalar();
        con.Close();
    }

    return bytes;
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not IsPostBack Then
        Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
        Using con As SqlConnection = New SqlConnection(constr)
            Using cmd As SqlCommand = New SqlCommand()
                cmd.CommandText = "select Id,Name from tblFiles"
                cmd.Connection = con
                con.Open()
                gvFiles.DataSource = cmd.ExecuteReader()
                gvFiles.DataBind()
                con.Close()
            End Using
        End Using
    End If
End Sub

Protected Sub Upload(ByVal sender As Object, ByVal e As EventArgs)
    Dim filename As String = Path.GetFileName(FileUpload1.PostedFile.FileName)
    Dim contentType As String = FileUpload1.PostedFile.ContentType
    Using fs As Stream = FileUpload1.PostedFile.InputStream
        Using br As BinaryReader = New BinaryReader(fs)
            Dim bytes As Byte() = br.ReadBytes(CType(fs.Length, Int32))
            Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
            Using con As SqlConnection = New SqlConnection(constr)
                Dim query As String = "INSERT INTO tblFiles VALUES (@Name, @ContentType, @Data)"
                Using cmd As SqlCommand = New SqlCommand(query)
                    cmd.Connection = con
                    cmd.Parameters.AddWithValue("@Name", filename)
                    cmd.Parameters.AddWithValue("@ContentType", contentType)
                    cmd.Parameters.AddWithValue("@Data", bytes)
                    con.Open()
                    cmd.ExecuteNonQuery()
                    con.Close()
                End Using
            End Using
        End Using
    End Using

    Response.Redirect(Request.Url.AbsoluteUri)
End Sub

Protected Sub Download(ByVal sender As Object, ByVal e As EventArgs)
    Using zip As ZipFile = New ZipFile()
        zip.AlternateEncodingUsage = ZipOption.AsNecessary
        For Each row As GridViewRow In gvFiles.Rows
            If (TryCast(row.FindControl("chkSelect"), CheckBox)).Checked Then
                Dim id As String = (TryCast(row.FindControl("hfId"), HiddenField)).Value
                Dim bytes As Byte() = GetBinaryData(id)
                zip.AddEntry(row.Cells(1).Text.Trim(), bytes)
            End If
        Next

        Response.Clear()
        Response.BufferOutput = False
        Dim zipName As String = String.Format("Zip_{0}.zip", DateTime.Now.ToString("yyyy-MMM-dd-HHmmss"))
        Response.ContentType = "application/zip"
        Response.AddHeader("content-disposition", "attachment; filename=" & zipName)
        zip.Save(Response.OutputStream)
        Response.[End]()
    End Using
End Sub

Private Function GetBinaryData(ByVal id As String) As Byte()
    Dim bytes As Byte()
    Dim conString As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Dim query As String = "SELECT Data FROM tblFiles WHERE id = @Id"
    Dim cmd As SqlCommand = New SqlCommand(query)
    Using con As SqlConnection = New SqlConnection(conString)
        cmd.Parameters.AddWithValue("@Id", id)
        cmd.Connection = con
        con.Open()
        bytes = CType(cmd.ExecuteScalar(), Byte())
        con.Close()
    End Using

    Return bytes
End Function

Screenshot