Changed wordpress URL, can't access site, wp-admin and FTP

Hi,

I made the common mistake of changing the home and site URL through wordpress, and now I can’t access the website, the admin panel and the FTP server (when I try accessing the latter, I get a message saying “directory listing denied”).

I have already read this guide

But failed to understand how can I access wp-config.php or the database (in order to fix the problem), if I can’t access FTP.

Any help would be appreciated.