CPU core problem pls help

I disabled my second CPU core and now i have no idea how to turn it back on.
It would really help me if anyone knows how to turn it back on.
If you guys are curious why i did it. I was trying to play "The Saboteur"
The game has problems with my hardware so i followed the instructions on the game's forum to find a solution but it didn't work so now I'm kinda stuck this way.
"Steps to turn off cores: (For Windows 7)

1.) Open MSCONFIG (You can open it by entering MSCONFIG in the search bar)
2.) Select the “Boot” tab
3.) Click on “Advanced Options”
4.) Check “Number of Processors”
5.) Select “1” from dropdown menu
6.) Click “Apply”
7.) Restart machine"

I figured i could just chose 2 processors in the dropdown menu later...only problem is it just shows only 1 processor