Black screen...can't see anything.

I just finished installing the game and was able to change my settings. I closed down the game to make sure my comp is running it on my nvidia gfx card abd not my intergrated. However now when i start the game the screen is black and displays nothing and i can only hear the intro. I tried to tab back and forth to see if the screen would show up but nothing. I am not puzzled as to what i did wrong. My gfx card is up to date. Anyone else experiencing this? Anyone can help?

Ok update got it to work but I had to switch back to integrated for me to see the screen but my game is not smooth. When i put it back to my nvidia card it just makes the screen go black. My gpu is a GTX 860M

-edit-

i guess i cant enjoy the game. if a mod sees this thread you are free to lock or delete it. Disappointed.