How do I set the default value of an input box using jQuery?

Reset by default clears a form but if you want to controll this behaviour yourself here is how you would do it. You need to use .val() Here are some examples of doing a single box reset and multiple box's using a wrapped set.

Example: http://jsfiddle.net/HenryGarle/ZTprm/

<b>Reset Single</b>

<input type="text" id="TextBox">
<button id="reset">Reset</button>

<hr>
<b>Reset Many</b>

<div id="Many">
<input type="text" value="1">
<input type="text" value="5">
<input type="text" value="2">
    <button id="ResetMany">Reset</button>
</div>


<script>
// Reset single
$("#reset").click(function (e) {
   $("#TextBox").val("Value"); 
});


// Resets many given a selector 
// Could be a form, containing div
$("#ResetMany").click(function (e) {
    var inputs = $("input", "#Many");

    for (var i = 0; i < inputs.length; i++) {
        $(inputs[i]).val("Value");
    }

});
</script>

You have to set attribute "value" of #email element, not the value itself.

$("#email").attr("value", "New value");

Reset clears all values of the form (default behaviour). If you want the values to be visible again, you need to set them again. So you need to call a method onclick of the reset button and fill the form again.