Sometimes for whatever reason it may be (the server exceeded the maximum number of connections due to not logging off properly, etc etc) you might need to do a remote restart of a machine.
To achieve this. The following two steps can be taken:
1. Set the admin password for the current machine you are on to be the same as the machine that you wish to shutdown.
2. Open a command prompt and type 'shutdown -i' you should then be given a graphical user interface to restart any server you wish to. The rest is pretty much self explanatory.