Our website has a white background with list of pages on it, themes are missing

It started when I began to change the WordPress adress (URL) and Site Address (URL) to https://corinthstone.com/worktops from https://corinthstone.com. Since I want worktops to be that landing opage of our website, When I clicked save, 500 internal server error appeared so I researched about that error and we rename the .htaccess after we log in, in ftp. after that deleting worktop from the url. and now, our website is a mess with a white back ground but the pages are on it, here is our website what will I do to solve this problem?