The gridview with data is not showing in ASP.NET

<!--Your gird on aspx page-->
<asp:GridView runat="server" ID="GridView1" AllowPaging="true" PageSize="10" AutoGenerateColumns="false" Width="420px">
<Columns>
<asp:BoundField DataField="Name" HeaderText="Name" />
<asp:BoundField DataField="DocumentContent" HeaderText="Document Content" />
<asp:BoundField DataField="Text" HeaderText="Text" />
<asp:BoundField DataField="demo" HeaderText="Demo" />
</Columns>
</asp:GridView>


//Your gird loading code logic

protected void Page_Load(object sender, EventArgs e)
{   
  fildata();   
}
 
protected void Button1_Click(object sender, EventArgs e)
{
  FileInfo fi = new FileInfo(FileUpload1.FileName);
 
  byte[] documentContent = FileUpload1.FileBytes;
 
  String name = fi.Name;
  using (SqlConnection con = new SqlConnection(cn))
  { 
    string query ="insert into Documents"+ "(Name,DocumentContent,Text,Demo) values(@Name,@doc,@Text,@Demo)";
 
    SqlCommand cmd = new SqlCommand(query, con);
    
    cmd.Parameters.AddWithValue("@Name", name);
    cmd.Parameters.AddWithValue("@doc", documentContent);
    cmd.Parameters.AddWithValue("@Text", TextBox1.Text);
    cmd.Parameters.AddWithValue("@Demo",TextBox2.Text);
    con.Open();
    
    cmd.ExecuteNonQuery();
    con.Close();
  }
}
 
//filldata is my method, which i made to show data in gridview. then i am calling that method on page_load time.
 
private void fildata() 
{
  DataTable dt = new DataTable();
 
  using (SqlConnection con = new SqlConnection(cn))
  {
    string show = "Select * from Documents";
 
    SqlCommand sq = new SqlCommand(show, con);
    con.Open();
    SqlDataReader sr = sq.ExecuteReader();
    dt.Load(sr);
    GridView1.DataSource = dt;
    GridView1.DataBind();
 
  }
}