Can anyone figure this out "Sound"

I have a Dell Demension 4550. I recently moved and had sound before I moved. Now there is no sound, I reinstalled the Drivers and also checked the speakers to see that they are operational. When I try to play a cd or anything I get a message "Sound Divice is being used by another program", but I dont have anything else open. I'm starting to believe that my Sound card went bad. Is this possible? Any suggestions. Also I do remember changing my Hard Drive around the same time I lost sound, and I'm unsure if I had sound after replacing the Hard Drive

Have you checked in device manager to see that the sound card is there ?