[There is nothing funny about it; you're learning and went where you shouldn't have, where I had readily assumed from both of your two linked OC installations that editing to undo what you did would be nothing new to you. I just noticed your edit to respell to funny.]
If you have a recent backup of header.tpl, just put that back into place. Maybe you're just using one or another of those infernal programs that pretend to write clean code but never will write it. However you did whatever you did, between a few days ago when appearances were normal and now when there is no style, is what I meant to undo -- undo what you did, the way you did it (by hand or by software, doesn't matter). A backup file would probably be quicker.
The simplest first thing to check is your theme. If it is not catalog/view/theme/default/, that needs to be changed to the appropriate catalog/view/theme/whatever/. If you're using the default theme, I haven't yet noticed what the problem actually is (where it's coming from). What I first suggested is NOT the problem. I looked at some other files to refresh memory, and the escaped /> (rather than common >) is springing from header.tpl the normal way.
Quick overview. Your header.tpl (category/view/theme/default/template/common/header.tpl) inserts your head section near the top of the page, above the body section, and the majority of your head section reads:
[code]
<head>
<title>Led Market, Led bulbs, Led lights , online shop.</title>
<base href="
http://ledbulb.ie/" />
<meta name="description" content="Best offer for Led lights. Replace your old bulbs to new LED lamps , LED bulbs are efficient and last for long." />
<link href="
http://ledbulb.ie/image/data/favicon ledbulb.jpg" rel="icon" />
<link rel="stylesheet" type="text/css" href="catalog/view/theme/default/stylesheet/stylesheet.css" />
<link rel="stylesheet" type="text/css" href="catalog/view/theme/default/stylesheet/slideshow.css" media="screen" />
<script type="text/javascript" src="catalog/view/javascript/jquery/jquery-1.7.1.min.js"></script>
<script type="text/javascript" src="catalog/view/javascript/jquery/ui/jquery-ui-1.8.16.custom.min.js"></script>
<link rel="stylesheet" type="text/css" href="catalog/view/javascript/jquery/ui/themes/ui-lightness/jquery-ui-1.8.16.custom.css" />
<script type="text/javascript" src="catalog/view/javascript/jquery/ui/external/jquery.cookie.js"></script>
<script type="text/javascript" src="catalog/view/javascript/jquery/colorbox/jquery.colorbox.js"></script>
<link rel="stylesheet" type="text/css" href="catalog/view/javascript/jquery/colorbox/colorbox.css" media="screen" />
<script type="text/javascript" src="catalog/view/javascript/jquery/tabs.js"></script>
<script type="text/javascript" src="catalog/view/javascript/common.js"></script>
<script type="text/javascript" src="catalog/view/javascript/jquery/jquery.cycle.js"></script>
<script type="text/javascript" src="catalog/view/javascript/jquery/nivo-slider/jquery.nivo.slider.pack.js"></script>
<!--[if IE 7]>
<link rel="stylesheet" type="text/css" href="catalog/view/theme/default/stylesheet/ie7.css" />
<![endif]-->
<!--[if lt IE 7]>
<link rel="stylesheet" type="text/css" href="catalog/view/theme/default/stylesheet/ie6.css" />
<script type="text/javascript" src="catalog/view/javascript/DD_belatedPNG_0.0.8a-min.js"></script>
<script type="text/javascript">
DD_belatedPNG.fix('#logo img');
</script>
<![endif]-->
<script type="text/javascript">
[/code]
Substantially the same interspersed with php appears in header.tpl and changing the latter will change the former. If you changed the theme from the default, catalog/view/theme/default/, change the latter to fit with what the new theme is.
