2004 Colorado Radio Problem

I bought my vehicle a little over 3 months ago, and have noticed once before that the audio from the radio would not play through my speakers....No big deal, it came back on quick......Today I was listening to the radio, and shut the truck off to go in the store.....When I came back out I turned the truck on and noticed that the lights on the radio kind of dimmed and brightend back up a couple of times, and no audio would come out of the speakers....The radio is still receiving a signal as it still lists the stations and what song is playing......The CD player will not work either.....It says track 1, or track whatever, but no sound comes out of the speakers.....Its just the basic system, it does not have an amp or anything.....Any ideas as to what the problem could be, or an easy fix for a not too auto savy person like me?