Hello,
I see you marked the topic as resolved. Were you able to fix the sites?
Anyway, you have 2 ways to fix a misconfiguration:
1. Delete the plugin directory wp-content/plugins/multiple-domain
. You should be able to do that from the hosting panel, from an FTP client, or via SSH. The downside of this technique is that it won’t be possible to install the plugin again since the configuration will still be in the database.
2. Remove the plugin configuration from the database using the following SQL query DELETE FROM wp_options WHERE option_name LIKE 'multiple-domain-%';
. This can be done from the hosting panel when PHPMyAdmin is available or using a MySQL client.
Regards