I changed my URL to an existing webpage

Hi.

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.

The page I need help with: [log in to see the link]