Failed to restart smbd.service: Unit not found. code example

Example 1: Failed to restart apache2.service: Unit not found.

You are using different service of apache.

run this if you are using the same service.

systemctl restart httpd
<----------------- Or ------------------>
apachectl restart

Example 2: Failed to restart sshd.service: Unit sshd.service not found

sudo apt-get install openssh-server