Any game I play is slow

Brendan - Updated by Brendan on 5/02/17 at 10:39 AM
So i factory reset my computer a while ago. Completely wiped it. And now when I started it up i realized it basically got rid of everything I need to do anything. My question is, what all do i need to play any game. This is a decent computer and it wont even run something like without being lag spiky. What do I need program wise.