how to display a message box telling he/she has exceeded her limit for today of entering into the application after 3 unsuccessful attempts by him/her in c# windows forms with sql server 2008

using System.Data.SqlClient;
using System.Management;
using System.Runtime.InteropServices;
using System.Net;
namespace Mini_Project
{
    public partial class frmLogin : Form
    {
int hit;
        public frmLogin()
        {
            InitializeComponent();
        }
private void btnLogin_Click(object sender, EventArgs e)
        {
            if ((txtPassword.Text == "password") && (txtUsername.Text.ToLower() == "admin"))
            {
                MDIParent1 h = new MDIParent1();
                h.Show();
                this.Close();
            }
            else
            {
                string username = txtUsername.Text;
                string password = txtPassword.Text;
                bool validUser = ValidateUser(username, password);
                if (validUser)
                {                   
                    MDIParent1 m = new MDIParent1();
                    m.Show();
                    this.Close();
                }
                else
                {
                    MessageBox.Show("Invalid user name or password. Please try with another user name or password", "Task", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                    txtUsername.Focus();
                }               
            }
}
private bool ValidateUser(string username, string password)
        {
            bool success = false;
			SqlConnection conn = new SqlConnection("Data Source=NPD-4\\SQLEXPRESS;Initial Catalog=Task;Integrated Security=true");
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = conn;
            cmd.CommandType = CommandType.Text;
            cmd = new SqlCommand("Select @count = Count(*) from [dbo].[UserDetail] where username=@username and password=@password and LoginAttempts >= 3 and datediff(day,row_upd_date,getdate())= 0", conn);
            cmd.Parameters.AddWithValue("@username", txtUsername.Text);
            cmd.Parameters.AddWithValue("@password", txtPassword.Text);
            cmd.Parameters.Add("@count", SqlDbType.Int).Direction = ParameterDirection.Output;
            conn.Open();
            cmd.ExecuteNonQuery();
			if (Convert.ToInt32(cmd.Parameters["@count"].Value) >= 1)
            {			
				 MessageBox.Show("User has exceeded his limits of login for today.", "Task", MessageBoxButtons.OK, MessageBoxIcon.Warning);
			}
			else
			{
				cmd = new SqlCommand("Select @count = Count(*) from [dbo].[UserDetail] where username=@username and password=@password ", conn);
				cmd.Parameters.AddWithValue("@username", txtUsername.Text);
				cmd.Parameters.AddWithValue("@password", txtPassword.Text);
				cmd.Parameters.Add("@count", SqlDbType.Int).Direction = ParameterDirection.Output;
				cmd.ExecuteNonQuery();
				if (Convert.ToInt32(cmd.Parameters["@count"].Value) > 0)
				{
					success = true;
					cmd = new SqlCommand("Update [dbo].[UserDetail] set LoginAttempts = (case when datediff(day,row_upd_date,getdate())=0 then LoginAttempts+1 else 0 end),row_upd_date=getdate() where username='" + txtUsername.Text + "'", conn);
					cmd.ExecuteNonQuery();
				}
				else
				{
					//No need to update LoginAttempts because this block will get execute only if username and password is not correct . 
					success = false;				
				}
			}
			conn.Close();
            return success;
        }
    }
}