Fatal error without mail

WordPress backup doesn’t help – I can’t restore the backup and I don”t know why.

Well, that depends on what tool you used to create the backup, and how the tool handles the restoration.

You could simply ask your host to restore a backup of your site for you if your hosting comes with such a backup.

If you need to use a WordPress plugin to restore the backup yourself, then you’ll first need to have a functioning WordPress site — even if it’s a blank, freshly-installed site — to activate the plugin and do the restoration.

How to disable the plugin?

The simplest way will be to rename or delete the plugin’s folder inside /wp-content/plugins/. This will effectively disable the plugin.

You’ll need (s)FTP, SSH, or the web-based File Manager in your hosting control panel (if any).

Alternatively, you can disable all plugins using your database management tool. Please see: https://www.ads-software.com/documentation/article/faq-troubleshooting/#how-to-deactivate-all-plugins-when-not-able-to-access-the-administrative-menus

I do not have access do myPHP or FTP.

How is your site hosted that you don’t have access to basic FTP?

If you simply don’t have the FTP connection credentials, please get in touch with your hosting provider and ask for your FTP connection details.

I don’t have FTP access because it’s not my wordpress but client’s and he’s on holiday now and god knows when he’ll be back. And the site needs to come back ASAP.

If you’re unable to receive the notification email to use the recovery link, you’ll absolutely need access to the hosting account to fix this.

There’s no way around that.

The problem is that the email with “what to do instructions” were to be sent is in a domain that no longer exists,

The email often contains a link you can click to put the site in “recovery mode”, which disables the plugin in question… allowing you to get in and fix the problem.

So, provided the server/site is able to send the emails to begin with (lots of servers aren’t configured to send email!)…

Then, if the domain is available and it’s not a TLD that costs an arm and a leg, you could spend the $10 or so to purchase the domain name again (if it’s available) and set up a catch-all to forward all incoming mails to your own email address. I don’t know if the “cost” of the site being down makes it worth the $10 to purchase the domain or not.

Yeah, I realize there are a lot of IFs here.