cannot display data between date in gridview c#.

Question

hello guyz , i need yor help , i cannot display the data between gridview when i filtering it in date , attach here is my source code in this project

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;


namespace onlinestudinformation
{
    public partial class studentaccountlst : System.Web.UI.Page
    {
        SqlCommand cmd;
        SqlConnection cn;
        SqlDataAdapter da;
        SqlDataReader dr;
        public void connectdb()
        {
            cn = new SqlConnection(@"Data Source=LAPTOP-93441BLD\HUSSIEN;Initial Catalog=studentinfodb;Integrated Security=True");
            cn.Open();
        }
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                this.connectdb();
                this.showlist();
            }

        }
        private void showlist()
        {
            this.connectdb();
            cmd = new SqlCommand("select *from tblOnlineuserregistration ", cn);
            dr = cmd.ExecuteReader();
            GridView1.DataSource = dr;
            GridView1.DataBind();
        }

        protected void btnload_Click(object sender, EventArgs e)
        {
            loadadata();
        }
        void loadadata()
        {

            this.connectdb();
          //  cmd = new SqlCommand(" SELECT lrn, lastname, firstname, middlename, email, username from tblOnlineuserregistration  where registereddate between '" + DateTime.ParseExact(TextBox1.Text, "dd-MM-yyyy", null).ToString("dd/MMM/yyyy") + "' and '" + DateTime.ParseExact(TextBox2.Text, "dd-MM-yyyy", null).ToString("dd/MMM/yyyy") + "'", cn);
            cmd = new SqlCommand(" SELECT lrn, lastname, firstname, middlename, email, username,registereddate from tblOnlineuserregistration  where registereddate between '" + TextBox1.Text + "' and '" + TextBox2.Text + "'", cn);

            // cmd = new SqlCommand("Select * from tbl_EmpPayroll where DateFrom between '" + dateTimePicker1.Value.ToString("MM/dd/yyyy") + "' and '" + dateTimePicker2.Value.ToString("MM/dd/yyyy") + "'", conn);
            dr = cmd.ExecuteReader();
            if (dr.Read())
            {
                this.connectdb();
                cmd = new SqlCommand(" SELECT lrn, lastname, firstname, middlename, email, username,registereddate from tblOnlineuserregistration  where registereddate between '" + DateTime.ParseExact(TextBox1.Text, "dd/MM/yyyy", null).ToString("dd/MMM/yyyy") + "' and '" + DateTime.ParseExact(TextBox2.Text, "dd/MM/yyyy", null).ToString("dd/MMM/yyyy") + "'", cn);
                GridView1.DataSource = dr;
                GridView1.DataBind();
            }
            else
            {
                dr.Close();
               // MessageBox.Show("error", "Message....", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                ScriptManager.RegisterStartupScript(this, this.GetType(), "script", "alert('No record has been found');", true);
            }
        }
    }
}