public class Utilities
    {
        public static void ResetAllControls(Control form)
        {
            foreach (Control control in form.Controls)
            {
                if (control is TextBox)
                {
                    TextBox textBox = (TextBox)control;
                    textBox.Text = null;
                }

                if (control is ComboBox)
                {
                    ComboBox comboBox = (ComboBox)control;
                    if (comboBox.Items.Count > 0)
                        comboBox.SelectedIndex = 0;
                }

                if (control is CheckBox)
                {
                    CheckBox checkBox = (CheckBox)control;
                    checkBox.Checked = false;
                }

                if (control is ListBox)
                {
                    ListBox listBox = (ListBox)control;
                    listBox.ClearSelected();
                }
            }
        }
          
          private void button1_Click(object sender, EventArgs e)
        {
             Utilities.ResetAllControls(this);
        }
    }