Changed Wordpress and Site Url, lost wp-login

Hi, thank you for your attention.
I'm a little bit panicked.

I'm working on a clients wordpress site.
And stupid me, I changed the wordpress and site url in general settings and of course now the server can't find the wordpress .php files and the wp-login.php

Can you jump into the ftp and Update the wordpress and site url, back to the original urls?
It's quite urgent.

I tried to follow these instruction but, I didn't get a response:
https://codex.wordpress.org/Changing_The_Site_URL

I don't know whether I'm putting in the wrong file-path to wordpress.