$(function (){
    
    $('#disableBtn').click(function(){
        $('#special_hide').attr('disabled', true);
    });
    
    $('#enableBtn').click(function(){
        $('#special_hide').attr('disabled', false);
    });
    
});

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <style id="special_hide">.special_hide { display: none; }</style>
    </head>
    <body>
        
        <button id="disableBtn">取消樣式</button>
        <button id="enableBtn">啟用樣式</button>
        
        <div class="special_hide">這個元素預設會因為樣式而隱藏</div>
        
    </body>
</html>

jsFiddle