Hi,
Do you use server cache or CDN? Try to clear that cache.
Turn on debug mode in WordPress – https://wordpress.org/support/article/debugging-in-wordpress/ to find out what error appears on your site, it will point you in the right direction what needs to be fixed.
Provide temporary wp-admin and FTP access, so we can take a closer look – create an account via Dashboard (Users > Add new) with administrator role http://prntscr.com/s3rc9m > provide us with username and password via the Private Content area http://prntscr.com/s5mao7 You can use any email for it. If you do not know how to create FTP contact with your hosting provider, they will help you.
Regards