SOS.. can't access WP page at all

Hi, i was trying to “fix” friend’s WP web-site, instead broke it more.. Can’t access it right now, says “The requested URL /index.php was not found on this server.”
In main WP settings I changed this main page address from https://www.sitename.net/web/ to “www.sitename.net” assuming it would somehow magically move all files and https://www.sitename.net will finally become accessable (as it was blank before).
Now I can’t even access WP at all..

Please, give a hand to a newbie idiot, how to fix this..
In addition, WP version I was working on wasn’t in English, which makes me harder to explain what I stupid did..