Occasionally you will come across a hung service
Most likely when you are updating, upgrading or restarting a section of a program. Exchange is a prime culprit of this, hanging information stores and the likes. So;
To kill the service you have to know its PID (Process ID). Finding this is easy in an administrative command prompt:
1: lookup the process ID
sc queryex *service name*
(Hint: you can find the service name by loading up services.msc and then opening the services properties dialog)
Step 2: Identify the PID
Halfway down the list will be the services associated PID
Step 3: kill the process with the taskkill command
taskkill /f /pid *PID*
This will force kill the hung service, which you can then re-start in services.msc