specifically overclocked and the one that was released summer of 2007?

it just happened yesterday. i was listening to some tunes then for some reason a certain part of this song was missing. i went up to both speakers and noticed that the left's sound is nowhere to be heard. both speakers are blasting out sound from the right. so right now, it's basically mono.

anyone experienced this before? any way to fix it? i'm pretty sure this happened before, but i can't remember what i did.

can anyone help me? i have no idea whatsoever.