ServiceController.Status Property

// Toggle the Telnet service -  
// If it is started (running, paused, etc), stop the service. 
// If it is stopped, start the service.
ServiceController sc = new ServiceController("Telnet");
Console.WriteLine("The Telnet service status is currently set to {0}", 
                  sc.Status.ToString());

if  ((sc.Status.Equals(ServiceControllerStatus.Stopped)) ||
     (sc.Status.Equals(ServiceControllerStatus.StopPending)))
{
   // Start the service if the current status is stopped.

   Console.WriteLine("Starting the Telnet service...");
   sc.Start();
}  
else
{
   // Stop the service if its status is not set to "Stopped".

   Console.WriteLine("Stopping the Telnet service...");
   sc.Stop();
}  

// Refresh and display the current service status.
sc.Refresh();
Console.WriteLine("The Telnet service status is now set to {0}.", 
                   sc.Status.ToString());