You can restart some of Plesk Web Hosting services directly from the control panel.
The services available for restart are:
In order to stop, start or restart some system service follow these steps:
Click on the RESTART SERVICES button on the web server administration page. The Plesk Web Hosting services restart page appears.
To start the service: click on the icon
(Start the service).To stop the service: click on the icon
(Stop the service).To restart the service: click on the icon
(Restart the service).
The current service state will be marked by an icon: 
(ON) for the service running, and 
(OFF) for the service stopped.