Problem with URLs – WordPress not detecting its home folder

Ok for some reason WordPress isn’t detecting it’s home folder. I don’t know what happened, but after I installed a new theme and clicked the “view site” link to preview the theme, then went back to the admin page, I got a 404 Not Found error. The link was correct and I checked the folder WordPress is installed in on my server, nothing was missing.
I then returned to the main index page of WordPress to find it had reverted to this. The url was fine, but then when I went to login the url for the login page showed up like this >> https://mydomain.com/wp-login.php when it’s suppose to look like this >> https://mydomain.com/news/wp-login.php
The weirdest part is that all the links to my blog posts and to the archives are correct, but all the admin pages aren’t.

I’ve contacted my web host about it, because WordPress had been installed through them, to see if they can sort out what the problem is. Unfortunately I’ve been waiting for a response about the issue almost all day, and I really would like to fix this problem ASAP. So if anyone here can help, I’d really appreciate it.