All images & themes are broken thumbnail

Last week I couldn’t log in to my site, had an error 503.
So I downloaded WordPress again and used FTP to keep my config settings and content.
Site came back ok, however all images were broken thumbnails (in media broken as well).
I updated to Nivana cryout theme settings and changed permission on the images (in case that’s why they weren’t loading). This didn’t work and now my theme (Nirvana) seems to be very basic: https://www.walcon.co.uk/

I have checked all other themes and they appear to just be html now.
What have I done wrong and how can I fix this?
My host is not contactable at the minute.