I just installed three themes made by Lucas-TDS and they worked fine untill I tried to change the names of the folders. Then suddenly the stylesheet seemed to go away. I mean it was still in the folder but it wasn't applied on to the theme which is a bit annoying. And I've tried to change back the names of the folders and everything but nothing happens.
It's happened before with themes from 7-Dana allthouhg I solved it somehow.

Is there anyway to prevent this?

http://intensitygaming.beigetower.org

Ummm....im new...but....
you should change your folder name prior to selecting the theme. The theme files are stored in a cache. So, if you change the folder name of the theme, that theme no longer technicaly exsists in XOOPS world, but the cache still does exsist. When the theme file is called, it uses the data found in the cache, and it will use the style sheet found in /themes/yourthemename. Since you changed your theme name folder, the style sheet no longer exsists in the same path, and can not be properly called.
i think.

Expanding on that, you should open up the theme.html file and make sure that you change any reletive links to the new name of the folder. There are many themes that use the theme name in a directoy call, and these need to be changed.

You will also have to check the style.css for any links to background images used (if any at all)

As mentioned, clear your /templates_c folder manually, or set it to update automatically through your System Admin>Preferences>General Settings.

Old template files will make your site appear broken if not cleared to reflect any recent changes.

You must rename all your files/folder to whatever they were cloned as. Make sure your in preferences "allow Update module template .html files from themes/your theme/templates directory?"
Now delete everything in templates_c and clear your browsers cache.

When you create a theme you need to clone an existing theme, usually default theme and you rename the clone to the name of the one you are installing. Once you do this you cant change anything. What you can do is upload different style sheets to the new theme folder. Simply call the existing stylesheet "oldestyle.css and the new one "style.css" You can do this as many times as you want to experiment with styles. If you prefer the original, simply rename it back to "style.css" Ive done this many times with no probelms. EXCEPT watch the images and cacheing. Keep clearing the templates_c and keeping things clean.
Richard