Missing css files list in css editor

Hi

I have been trying to edit the css files using the the css editor from /apparence/css edit. But there is no list of files to choose from and edit from the right side of the page, just backups entries. The other night, by chance, all a sudden, there was the whole css, php list of files that could be edited. Now it has disappeared? How do I get it back? Any idea?

Thanks

Didier