Wordpress website issue with file management to be uploaded

Hi. My website www.charlenecollet.com is not working because of a file management error. The server and domain are fine (Hostgator) but it seems that my files need to be uploaded, however, I do not even have access anymore to the WordPress back office. Can you please help me resolve this? I'd like to find someone who can explain me the steps through as well for me to learn.
Best,
Charlène