<body>
<header>
<div class="block">Hello!</div>
<div class="block hidden">Салем!</div>
<div class="block hidden">Привет!</div>
<div class="block hidden">Merhaba!</div>
</header>
<script src="js/jquery.min.js"></script>
<script src="js/js.js"></script>
</body>
$('.block').on('click', function() {
var _this = $(this);
var parent = _this.parent();
var el = parent.find('.block:not(.hidden)').toggleClass('hidden');
if(el[0] == parent.find('.block').last()[0]) parent.find('.block').first().toggleClass('hidden');
else el.next('.block').toggleClass('hidden');
})