Edit in JSFiddle

$(document).ready(function() {
    var dvjQuery = null;
    $('#btnAttach').attr('disabled','disabled');
    
    $("#dvjQuery").hover(function() {
        $(this).addClass('highlight');
    }, function() {
        $(this).removeClass('highlight');
    });

    $('#btnDetach').click(function() {
        dvjQuery = $("#dvjQuery").detach();
        $(this).attr('disabled','disabled');
        $('#btnAttach').removeAttr('disabled');
    });
    
    $('#btnAttach').click(function() {
        $("#dvParent").html(dvjQuery);
         $(this).attr('disabled','disabled');
        $('#btnDetach').removeAttr('disabled');
    });
});

<form>
    <div id="dvParent">
   <div id="dvjQuery">jQuery By Example is a good blog to learn jQuery. </div>
    </div>
    <br/><br/>
    <input type='button' id='btnDetach' Value=' Detach Div ' />
    <input type='button' id='btnAttach' Value=' Re-attach Div ' />
    <br/><br/>
</form>