How to Fix CS:GO vac was unable to verify your game session

opened cs:go to play and get rid of routine and boredom I clicked play to start the match I got an error says :

vac was unable to verify the game session

I started looking for a solution and I found a lot of them and people re-installing their games and steam launcher and then I came across this solution that was easy and worked for me.
that explanation on the video above.