401 error persists despite repeated attempts to solve this

The website in question is http://www.empsolutions.ca.

Was running fine up until a few hours ago, when users trying to access /wp-admin are redirected to the 401 Authorization required page. The site itself is running fine and the email servers are running fine.

Here's what I've tried:

Disabled Wordfence plugin Disabled all plugins Created new user in database (no use since can't even get to login screen) Spoken to hosting provider to determine no IPs of mine were blocked Deleted .htaccess file Renamed child theme

None of these things have worked... grateful for any suggestions.