General settings error

I try to change WordPress Address (URL)that was: http://www.ultraeco.com.br/site to http://www.ultraeco.com.br/ and when I save I receive the message: The system cannot find the file specified, and the URL: http://www.ultraeco.com.br/wp-login.php?redirect_to=%2Fsite%2Fwp-admin%2Foptions-general.php&reauth=1

When I try to enter again to restore the configuration I can´t login in the dash panel because, I believe that the WP looses the reference (the WP blog is install in the “site” directory, so now I can´t acess the WP panel.

My url is:

and it lost all the images, diagramation, etc…

I am use the Avada Theme.

How can I restore the site?
Can I change some archives acessed by ftp to fix that?

Please, help me because it´s almost ready and I make this idiot error.