WirdGirl

No this isn’t caching.

If I’m on the same machine and I log out of wordpress admin, I won’t be able to see anything except the homepage. There’s a redirect happening.

Same goes for other browsers, other users, even people who’ve never visited the website before.

There seems to be a reference to the site host that I’ve screwed up.

I used a Search and Replace plugin to find the IP address and replace it with the domain name, and I can’t ask for support there because the plugin has been pulled.

To add to what Andrew said – if anyone has access to the email accounts, you can trigger password resets and regain access.

Your hosting provider should also be able to help – you may have to have proof that your tech guy was acting on your behalf (invoices / contract / etc).

Do you have access to the email account used by any of the admin accounts?
Or to the email address used with the hosting company?