Moving WordPress from subdomain to root has gone wrong

I have followed the Moving_Wordpress, but something has gone wrong!
My subdomain was https://www.testing.aku-kur.dk and I moved it to https://www.aku-kur.dk by FTP and followed the steps in the Guide.
I have change the two Urls to: https://www.aku-kur.dk in the admin panel first and after moved the 3 folders with all the contents. But now I can’t get to the admin panel anymore.
When i type: https://www.aku-kur.dk/wp_admin or https://www.aku-kur.dk/wp_login I just get a blank page with text ERR_NAME_NOT_RESOLVED.

Can anyone please help me, as my customers can’t see any of my pages right, at the moment and I can’t fix it?

I don’t know if it has any importens but my theme is MH Squared.