mac keyboard stops working

this has been happening for a year already (since i got my computer). my mac would just suddenly, with NO pattern (ive been trying to find one since it happened), have the computer and trackpad frozen. The lights on the keyboard would just turn itself off. everything on screen is fine - any video game going on will continue and any youtube video would continue like usual, except i cant do anything that is not shutting it down (power button still works). restarting it works fine but is extremely annoying since theres no way to stop it. ive been banned for smurfing in a game already cause of this. HELP ME!!!