If you lose access to your Mac, first determine whether the problem is remote access, credentials, networking, or the operating environment itself. Many access problems come from a changed password, an incorrect host, or a disabled remote service rather than from a full platform failure.
If normal recovery fails, your next step may be to use whatever recovery or reinstall workflow is available for the service. Be careful with destructive actions if the system contains data you still need.
If the service is important, keep your backup and recovery plan ready before access problems happen.