I’ve checked that the files I want are there via both FileZilla and your File Manager; the files are there and not empty. The site was working a few hours ago.
You said your website is redirected to ?z, which is the advertisement page. After you have waited for up to 72 hours, your site will start working. I think admin did nothing. It is just your browser DNS cache is removed! Hope you will understand!
It looks like one of the nameservers, ns4.byet.org is malfunctioning, and returning bad DNS results.
I just removed ns4.byet.org from our own domains (epizy.com, rf.gd, etc.). However, due to DNS propagation it can take a while for your website to be available again.