Unit sshd..service could not be found. Unit service.service could not be found.

It seems like there is a typo in the command you are running. Instead of typing `sshd..service` or `service.service`, try typing `sshd.service` or the name of the specific service you are trying to use.

For example, to start the sshd service, you can use the following command:

sudo systemctl start sshd

To start a different service, replace `sshd` with the name of the service you want to start.