I do have a desktop with xp, but I can't heard system sounds anymore, sound blaster 16, code 10 can not start?

I already try everything, but I just can't fix the problem, the computer can play cd's and DVDs but if a try to hear a video for example from the web is not possible, it report a code 10 (the sound card can't start), why? I don't know can anyone help out?....thanks.