You could try using disk mounting software to your computer such as Alcohol52% which is available for free from the Internet. With that you can install a "virtual drive" that can create an image of the cd. Use the program to create images of all four cd's in the set (if it's the same as my daughters set, you will either have four cd's or two dvd's), either way you will need to create images of each disk and store them on your hard drive. Then you can use Alcohol or another diskmounting program to install and play the game.
If your CD/DVD is too damaged to be used altogether, there is no other option but to purchase a new set. Harvey Norman (Australia) have it currently for $10 a set, so it's not much to replace.