Accidentally changed URL!

I accidentally copied a google search console code onto the end of my URL in the general settings page. The webpage has now lost all formatting and looks like a basic text site.
I quickly changed the mistake thinking that this would resolve the issue but now the website’s stuck like that and it’s no longer letting me login to change anything. I’m terrified that it’s stuck that way and the worst of it is I don’t have any access to the latest theme as there was an error with the last upload and the maker of the theme had to upload the latest version himself. So I don’t have the files to edit and re-upload to the site. You can see the website here: http://www.scratchworkstheatre.co.uk

Any help would be much appreciated because I’m completely stuck!