mute

I'm so sad now. My computer speakers turned mute all of a sudden. It was fine before I fixed in the new DVDwriter that I bought today. *sigh* I'm feeling really helpless. *sobs* Now I can't listen to my MP3s nor CDs nor watch my animes because there ain't any sound coming out of the speakers. Can anyone help me? I've already plugged back all the wires/plugs or whatever you call those into their designated points. Why no sound? Even my brother haven't any idea why. *sobs* During the process of plugging in those wires, I've damaged my keyboard plug. Luckily my brother had a new spare keyboard which he reluctantly lend it to me for the time being. Perhaps I need someone to come take a closer look at my CPU. Guess I gotta make do without any sound for now till help arrives. HELP!!!