protected void btnAllStock_Click(object sender, EventArgs e) { //create an instance of clsStockCollection clsStockCollection Stock = new clsStockCollection(); Stock.ClearFilter(); lstStock.DataSource = Stock.StockList; //set name of primary key lstStock.DataValueField = "ItemId"; //set name of field to display lstStock.DataTextField = "ItemName"; //bind data to the list lstStock.DataBind(); }