Have you tried reinstalling your theme? Based on the link you provided, it looks like a relatively benign PHP hack of <p><?php the_tags(); ?></p>. This might mess up the page display, but it shouldn't change your media linkages. Reinstalling the theme, or copying fresh copies of the files you modified, would restore the files.
Regarding the CSS you posted above, that too would not effect images. Unless the images were wrapped in class="tags" references. Oh, and I tried the link you provided. I see images fine. So, this might just be a caching issue in your browser.