Computer problems, lagging horribly all of a sudden. Please help?

Okay! So earlier, I was playing Ark: Survival Evolved on my gaming laptop. It is a Lenovo ideapad y700, Intel core i7, Nvidia GeForce GTX. It runs games amazingly, but occasionally freezes with big games like Ark. Normally I wait it out and it just I freezes on its own. However, this time it didn't. So, I pressed ctrl+alt+delete to try and exit the game and/or open task manager. But it didn't do anything. I also tried shift+tab to try and change Windows. Still nothing. So I did what I had to do and I forced the laptop to shut down by holding the power button. I left it off until I returned to my dads house (I was at a friends house) and then turned it back on, just to notice that the computer is lagging terribly. I'll open a program such as powersaves (for my 3ds) and it takes forever to do anything. Even in Google chrome, I'll have 2 tabs open and try to click on a new tab, and it freezes up. Before I played ark earlier it was fine. Someone please help