Recover MS Word disappeared files Using MacOS High Sierra while had 6-7 unsaved word(V-16.23) document where I was working on. coz of my processor fan speed, I tried to check the 'Activity Monitor'. and found WindowServer is using almost 1gb so killed that process.
Then I realized all was for my unsaved word documents....I'm literally crying after losing all my data, Can someone please help me out?
You can hope that you had auto-save enabled in Word. If that is the case, you should be able to start Word again, and it will ask you if you want to recover those documents. You can also check the auto recovery folder manually for files:

/Library/Containers/com.microsoft.Word/Data/Library/Preferences/AutoRecovery/


If you have Time Machine enabled, try starting it up and seeing if you have got versions saved of the documents there. Even when you haven't got the external backup drive connected, Time Machine will still save backups locally. However, it can ofcourse only do so if your documents were actually saved to files before Word were closed.

In regards to your actions: The usage of RAM (for example 1 GB) has absolutely nothing to do with processor fan speed. The WindowServer manages all application windows on screen, including for example Word and any other application. Killing it essentially kills all graphical programs, and you're logged out and will have to login again and start over.