auto serial number in listview

See more:

C#3.5

problem setting automatic serial number in listview, can add the serial number but while deleting ex. serial no like 1 2 3 4 5, if i delete the row having serial no 3, serial number 4 5 doesn't convert into 3 and 4 automatically

private void btn_Addtocart_Click(object sender, EventArgs e)
        {
            try
            {
                if (txtProductName.Text == "")
                {
                    MessageBox.Show("Please retrieve product name", "Input Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    return;
                }
                if (txtSaleQty.Text == "")
                {
                    MessageBox.Show("Please enter no. of sale quantity", "Input Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    txtSaleQty.Focus();
                    return;
                }
                count = ListView1.Items.Count + 1;
                int SaleQty = Convert.ToInt32(txtSaleQty.Text);
                ListViewItem lst = new ListViewItem(count.ToString());
                if (ListView1.Items.Count == 0)
                {
                    lst.SubItems.Add(txtProductName.Text);
                    lst.SubItems.Add(Company.Text);
                    lst.SubItems.Add(txtPrice.Text);
                    lst.SubItems.Add(txtSaleQty.Text);
                    lst.SubItems.Add(txtTotalAmount.Text);
                    ListView1.Items.Add(lst);
                    Company.Text = "";
                    txtProductName.Text = "";
                    txtPrice.Text = "";
                    txtAvailableQty.Text = "";
                    txtSaleQty.Text = "";
                    txtTotalAmount.Text = "";
                    textBox1.Text = "";
                    txtSubTotal.Text = subtot().ToString();
                }
                else
                {
                    lst.SubItems.Add(txtProductName.Text);
                    lst.SubItems.Add(Company.Text);
                    lst.SubItems.Add(txtPrice.Text);
                    lst.SubItems.Add(txtSaleQty.Text);
                    lst.SubItems.Add(txtTotalAmount.Text);
                    ListView1.Items.Add(lst);
                    Company.Text = "";
                    txtProductName.Text = "";
                    txtPrice.Text = "";
                    txtAvailableQty.Text = "";
                    txtSaleQty.Text = "";
                    txtTotalAmount.Text = "";
                    textBox1.Text = "";
                    txtSubTotal.Text = subtot().ToString();

                }
                ListView1.Sort();
                ListView1.Refresh();
                ListView1.Update();
            }

            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }



  private void removeFromListToolStripMenuItem_Click(object sender, EventArgs e)
        {
           
            foreach (ListViewItem listviewitem in ListView1.SelectedItems)
            {
                listviewitem.Remove();
            }                
	    }

[edit]Code block added - OriginalGriff[/edit]