I had a modified Twenty ten theme on my blog but when i wanted to switch it to another theme it all went wrong.
When i go to Appearance > Themes now, I only see the current theme (Twenty Twelve) and no option to change theme or see a preview of the other available themes. Twenty Ten stopped working or at least doesn't show up anymore.
I've tried deactivating all plugins, but with all deactivated I still get the same options in the Themes manager. Screenshot
I already replaced the themes.php / theme-install.php files on the server, but nothing changes.
Any help is welcome as I see no other options on how to solve this.