What's wrong with my guitar and how do I fix it?

I was playing my electric guitar (Epiphone Les Paul Special-II) when it suddenly stopped playing. On the clean and drive channels, the sound suddenly turned extremely low to point of being barely hearable. It doesn't sound as bad with overdrive on, but I still, I have no idea why this happened or what to do. The guitar is only 9 months old and has been fine since I got it. What's the problem and what should I do?