javascript function if ,else conditions

I am new to programming, I have created following Javascript function from scratch. But, it not executing correctly.It has some errors,but,I can't clear the errors.please help me,

<script type = "text/javascript">
        function GetSelectedRow(lnk) {
            var row = lnk.parentNode.parentNode;
            if (row.cells[0].innerHTML == "checkbox")
            {
                var ItemCode = row.cells[1].innerHTML;
                var ItemName = row.cells[2].innerHTML;
                var Unit = row.cells[3].innerHTML;
                var Price = row.cells[4].innerHTML;
                var StockQty = row.cells[5].innerHTML;
                document.getElementById('<%=TxtICode.ClientID %>').value = ItemCode;
                document.getElementById('<%=TxtIName.ClientID %>').value = ItemName;
                document.getElementById('<%=DropDownUnit.ClientID %>').value = Unit;
                document.getElementById('<%=TxtPrice.ClientID %>').value = Price;
                document.getElementById('<%=TxtStockQty.ClientID %>').value = StockQty;
                return false;

            }
           else (row.cells[0].innerHTML != checkbox)
            {
                 var ItemCode = row.cells[0].innerHTML;
                var ItemName = row.cells[1].innerHTML;
                var Unit = row.cells[2].innerHTML;
                var Price = row.cells[3].innerHTML;
                var StockQty = row.cells[4].innerHTML;
                document.getElementById('<%=TxtICode.ClientID %>').value = ItemCode;
                document.getElementById('<%=TxtIName.ClientID %>').value = ItemName;
                document.getElementById('<%=DropDownUnit.ClientID %>').value = Unit;
                document.getElementById('<%=TxtPrice.ClientID %>').value = Price;
                document.getElementById('<%=TxtStockQty.ClientID %>').value = StockQty;
                return false;
            }

        }
    </script>