<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script>
$(function() {
$('input').attr('readonly',1);
});
</script>
</head>
<body>
<input value="Измени" />
</body>