If you do have not ssh access to your server, you can do nothing. In this case, you have to contact your service provider support to check the status of sshd service and attempt to run it. They should have direct access to your server.
Issue here is probably that PermitRootLogin in the sshd_config file is set to "no". You need an exception for 127.0.0.1 for it as described in https://support.plesk.com/hc/en-us/...-identification-read-Connection-reset-by-peer
But as IgorG said if you do not have SSH access, your provider needs to set-up the exception in SSH configuration for you.