How do I send an item to a new line in the listbox

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C#

I have this code which sends items from a cell in the database which is in listform to a lsitbox.
But when it loads in the database it appears in a long list rather than each new item going to a new line..

Can any one help?

private void ItemCBx_SelectedIndexChanged(object sender, EventArgs e)
{

    Listbox1.Items.Clear();
    MAcon.Open();
    OleDbDataAdapter da = new OleDbDataAdapter("Select Process from [Product Family] Where [Product Name] = @ProductName", MAcon);
    da.SelectCommand.Parameters.AddWithValue("@ProductName", ItemCBx.SelectedItem.ToString());
    DataTable dtbl = new DataTable();
    da.Fill(dtbl);

    if (dtbl.Rows.Count == 1)
    {
        Listbox1.Items.Add(dtbl.Rows[0][0]);
    }
    MAcon.Close();
    Listbox1.Show();
    Listbox1.Text.ToString().Split(',').ToList().ForEach(r => Listbox1.Items.Add(r.Trim()));
    //           Define.SelectedIndex = 1;
}

What I have tried:

Listbox.Text = Listbox1.Text.Replace(",", Environment.NewLine);