Start the process WindowServer per Terminal I have to start the WindowServer Via the Terminal:

/System/Library/Frameworks/ApplicationServices.framework/Frameworks/CoreGraphics.framework/Resources/WindowServer


I can not use 

killall -HUP WindowServer


because the process is not running.
Can it without reboot the system?
Found it by:
https://discussions.apple.com/thread/3466991?tstart=0

launchctl unload /System/Library/LaunchDaemons/com.apple.WindowServer.plist  
launchctl load /System/Library/LaunchDaemons/com.apple.WindowServer.plist