No theme is displayed on my website

Hello, I have had my website for 2 years and it always worked fine, I use the Bretheon theme, all of the sudden, 9 days ago, my website appearance changed drastically, I realized that none of the themes (Not even the Twenty ones) work, my website now looks like plain text https://www.elofriends.com, some pluggins stopped working as well.

I have already tried deactivating every plugging and it didn’t fix the issue, I have read a lot of posts about the problem and I think that my stylesheet is not working properly, I’m not sure what happened as the site have been running with the same configuration for 1 year and I changed nothing, on the FTP I can see that the stylesheet is there and the permission seems fine (755) I have also tried checking the .htaccess file and it only says “deny from all”, I have tried over 50+ themes and none of them work

Thanks