Sound problem

I have reformatted my hard drive, I’ve reinstalled Windows XP and everything,since then I start having sound problem. I called it “sound problem” because I do not know how to call it. In reality, sounds do come out from my speakers, but for example if I put a cd and try to play it, no sound will come out. It seems like Windows doesn’t recognize my sound card. I hear music but I do not know where that music comes from. Once I turn on the computer, before loading Windows,music start playing; and when windows starts, usually that’s a theme song, I don’t hear that theme song. Please help me.
Note: I have an integrated sound card.