Customizer and preview don't work

Hi! I changed the company where I bought my domain and moved the hosting to Hostgator. I loaded some themes, but the only thing I see when I load the page (www.regalaunmomento.com) is the page that I designed previously and loaded with a ftp program. I have loaded wordpress again, deleted cache, loaded wordpress again in Hostgator, but nothing works. When I go to the customize page, I only see a grey little spot loading and can’t see the preview. I tried with the original theme, but it doesn’t work either. What can I do? Thank you very much.