Problem is that you are not adding new row to the ListView.Items collection.
listView1.Items.Add(row);
if (dt.Rows.Count > 0)
{
ListViewItem row = new ListViewItem();
for (int i = 0; i < dt.Rows.Count; i++)
{
row.SubItems.Add(dt.Rows[i][0].ToString());
}
listView1.Items.Add(row);
}