Completely different website on mobile

So if I go to dashboard pages I see for example : about us, services, contact etc. Like 3 total.
I can access and edit those.
But when I visit mobile home page: everything is same, except logo, the menu items LOOK almost the same, but instead of contact, it’s called “contact us” and the URL is contact-us..
Instead of “About” there is “about-us”..
The Problem is I don’t see those pages in the dashboard!
And another “funny” thing is I can’t login via WordPress admin page, only via Cpanel and no matter if I create new user with admin access it won’t let me in anyways.
There is a messuo somewhere, I guess..
Have never seen this before.
Have something in mind like a database problem ??? (old, deleted, pages showing up). Someone tried to install new WP above old installation without updating database. Or failed database update.. idk..
I’m not the owner, I was asked to fix some pages and troubleshoot PayPal.
If he will let me, I’ll post the link.
Meanwile the problem posted “as is”.