Template stripped off pages

I just switched to WP, and had the template modified and all post imported. I then explored some plug-ins, with the result that most of the template is stripped off the public pages (colors etc. gone, only the plain text left.) Looking at the source code, there is nothing there apart from the plain text from the posts.

I uninstalled the plugins, and even imported a backup of the database which I made earlier this morning, but no change.

When I go to the Theme Editor, I can still see the template files there, but when I go to Themes, I only see the titles of each theme and no graphics.

The two plug-ins were Tidy-Up (cleaning up HTML) and WP-Cache. I activated WP-Cache, then ran Tidy-Up, and then reloaded to the see result – which was these stripped pages. Unfortunately, I am not sure which plug-in is responsible.

Any help is appreciated.