I have a audio problem!?

My computer has a problem. It doesn't have ANY sound! I was in the middle of a program and it suddenly didn't have any sound. It wasn't the program I used because I checked if there was a virus but there wasn't any. I checked all the audio software's and speakers and even tried the earphones! Nothing will produce ANY sound. Do i need to format my computer or debug my sound systems? Anyopne have any idea? HELP PLEASE!