int count = userlist.Rows.Count;

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace WindowsFormsApplication1
{
    public partial class Login : Form
    {
        TextBox Login_fld = new TextBox();
        TextBox Password_fld = new TextBox();
        Button Login_bttn = new Button();

        public Login()
        {
            this.Size = new Size(400, 200);
            Login_fld = new TextBox();
            Password_fld = new TextBox();
            Login_bttn = new Button();


            Login_fld.Size = new Size(50, 100);
            Login_fld.Location = new Point(10, 10);

            Password_fld.Size = new Size(50, 100);
            Password_fld.Location = new Point(10, 40);

            Login_bttn.Location = new Point(150, 10);

            InitializeComponent();

            this.Controls.Add(Login_fld);
            this.Controls.Add(Password_fld);
            this.Controls.Add(Login_bttn);

            Login_bttn.Click += new EventHandler(Login_bttn_Click);

        }

        private void Login_bttn_Click(object sender, EventArgs e)
        {
            try
            {
                Getdata();
                FormMain FormMain = new FormMain();
                this.Close();
                FormMain.Show();

            }
            catch
            {
                MessageBox.Show("Error occured, application will be stopped");
                Application.Exit();
            }
        }

        private void Getdata()
        {
            string connString =
            @"server=.\SQLExpress;AttachDbFilename=C:\Program Files\Microsoft SQL Server\MSSQL11.SQLEXPRESS\MSSQL\DATA\warranty.mdf;Database=warranty;Trusted_Connection=Yes";
            SqlConnection conn = new SqlConnection(connString);
            SqlDataAdapter Loginadapter = new SqlDataAdapter();
            SqlCommand Logincommand = new SqlCommand("select * from Users_List where user_login = @login and user_password = @password" , conn);
            Logincommand.Parameters.Add("@login", SqlDbType.Char).Value = Login_fld.Text;
            Logincommand.Parameters.Add("@password", SqlDbType.Char).Value = Password_fld.Text;
          
            Loginadapter.SelectCommand = Logincommand;

            DataSet wrtydataset = new DataSet();
            conn.Open();
            Loginadapter.Fill(wrtydataset);
            conn.Close();

            DataTable userlist = wrtydataset.Tables["UsersList"];
            int count = userlist.Rows.Count;
            if ( count < 1)
            {
                MessageBox.Show("User/login incorrect");
                Application.Exit();
            }
        }
    }
}