That's not a correctly formatted comment
To comment something out, use this:
{* Commented Out Code *}
So in your case, it would be:
<BR><BR>{/if} {if $product.forsale ne "B"} {*{include file="buttons/add_to_cart.tpl" style="button" href="javascript
: if(FormValidation()) document.orderform.submit();"}*} {if $login ne "" and $active_modules.Wishlist ne ""} {include file="customer/add2wl.tpl"} {/if} {else}
That's the add to cart button though, not the buy now button.