Just use the defaultValue property:
var default_value = $(this).prop("defaultValue");
Or:
var default_value = this.defaultValue;
<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>