There is nothing wrong with the code the t-p posted. It does however, need a modicum of PHP knowledge to add the code to a pre-populated functions.php file.
In other words – you broke your site. Swearing and throwing a tantrum won’t change that. But if you have re-uploaded an unmodified copy of functions.php to your current theme, it will fix the error. Remember to press CTRL and F5 simultaneously when viewing an updated page/site. Or try emptying your browser cache. This should ensure that your web browser fetches a fresh copy of the page rather than serving up an out-dated copy from your own cache.
[EDIT: And that wasn't a double post above. Some of us saw the original.]