نه اینطوری

namespace Test

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        private int RandomNumber(int min, int max)

        {

            Random random = new Random();

            return random.Next(min, max);

        }

 

        private void button1_Click(object sender, EventArgs e)

        {

            label1.Text = RandomNumber(1000,9999).ToString();

        }

    }

}