Sound wont work after swicthing to 64 bit os

Hello,
Im having a major problem. I have recently installed 64 bit windows 7 ultimate on my computer. The sound will not work, i have installed the disk that came with the computer. This is what it says, spidf/digital sound. When i plug in a sound cord to the computer, nothing will come out of the speakers. I know it not the speakers because ive tried it with my ipod. I try to play anything, nothing. Please help!
thank you!