If for a PC (and not for WII as it shows above), there is nothing you can do really, except demanding your money back. A lot of games on the PC require CD key codes, that code is usually inside the box or on the backside of your manual (please look there and see if you can find it). If you would have the code, it might say it is already used. That means you cannot install it unless the code gets deactivated on the PC of the guy that sold you this.
But if you don't even have the code (backside of manual or above the disk in the box), then you cannot start the game without buying a new one first, or getting that code while it has not been activated on another computer.
Answers & Comments
If for a PC (and not for WII as it shows above), there is nothing you can do really, except demanding your money back. A lot of games on the PC require CD key codes, that code is usually inside the box or on the backside of your manual (please look there and see if you can find it). If you would have the code, it might say it is already used. That means you cannot install it unless the code gets deactivated on the PC of the guy that sold you this.
But if you don't even have the code (backside of manual or above the disk in the box), then you cannot start the game without buying a new one first, or getting that code while it has not been activated on another computer.