Directory Listing Denied

So an acquaintance asked me for some help on his website. I’m a web app developer with 2 years of experience, but have never touched wordpress before. When you go to his site: https://www.duiseattle.com/ you see “Directory Listing Denied”. And when you go to his admin login page: https://duiseattle.com/wp-login.php you get a 404 error “The page cannot be found”.

He had been paying a guy to update his site, but the guy seems to have mysteriously disappeared. The only page that is showing up at all is https://www.duiseattle.com/content/ but it seems to have lost all of its styles. I’m not sure where to even start, because he doesn’t know the email address associated with his wordpress account. Any help would be greatly appreciated. Thank you!