My b2evolution Version: 1.8.x

Hi,

I was just adding a new sidebar item and trying to modify the CSS of the sidebar items, and my categories just disappeared. No PHP error, just nothing being displayed.

The only files I modified were:
_categories.plugin.php
_categories.php
_linkblog.php

and I undid all my changes and reuploaded to the proper directory (the only thing I did was change the <DIV> class). When that didn't work, I even went to my original source files and reuploaded those. To no avail.

I have 3 different skins, and whatever I did is affecting all 3 skins, 2 of which I didn't touch while making these changes.

Here's one of my sites, as you can see, towards the top right under "Serengeti" there are no categories, instead just displaying my Google AdWords code.
http://www.serengeti.in/

Any idea what could have happened? This is version 1.8.1 and I have doublechecked in my admin that all categories and posts are indeed still intact, it's just the display that's messed up and I'm baffled.

Many thanks in advance.
Bryan