Edit in CSS

defaults back to the original version.

Use an ftp client to change it. Save your changes to style.css, then refresh your browser.

Or… change permissions on the file to allow you to use the WordPress theme editor.

http://codex.wordpress.org/Editing_Files#Using_the_Theme_Editor

I changed the url naming convention and now none of the links work.

Update your permalinks.

http://codex.wordpress.org/Using_Permalinks