My agency have a website: . I have in the past weeks been working on a new website, which i called update. Then i tried to change the URL for the new website to , thinking it was not possible as another webpage already had this name, but i worked and now my new website has disappeared. My login to wordpress no longer works and i can only use the login to the old designunit.dk-page. Any chance any one know how to fix this?

Thank you so much in advance.

You must have changed the URL from WordPress General Settings so now it is saved in database. Now, you can fix it by finding the fields site_url and home in options table and then change the address there to your desired one.
You can check the following link as well to check how to do it using database:
https://www.inmotionhosting.com/support/website/wordpress/wordpress-changing-the-site-url-and-home-settings

Thanks