the other morning i climbed inside my car and realized that the radio was not working as it had the night before ( less then 12 hours) it still lights up and everything and i can hit the recall button and have it show the time but other than that it does nothing else. one of my friends told me that it might be locked. so the first question i have is how do i know if it is locked or not...and the second is does anyone know where i can find a wiring diagram of what color of wires do what back behind the radio

 

If it was locked, it would say "LOC" on the display.

 

Turn the radio on, hit the seek to try another strong station, turn volume way up, adjust balance and fader to try each speaker individually, and then try with a CD. did you check the fuses? If you have the factory add on amp, and the fuse is blown, you'll get no sound.
Wiring for 2001 and older, from HillbillyinOhio:
For Blazers and S-10s (including Bravada, Sonoma, Jimmy, Full-Size) the actual stereo wiring is as follows Constant 12V+ Orange
Switched 12V+ Yellow
Ground Black
Illumination Gray
Dimmer Brown
Antenna Trigger Pink
Antenna Right Front
Front Speakers 4" x 6" Dash
Left Front (+) Tan
Left Front (-) Gray
Right Front (+) Light Green
Right Front (-) Dark Green
Rear Speakers 6" x 9" Side Panels
Left Rear (+) Brown
Left Rear (-) Yellow
Right Rear (+) Dark Blue
Right Rear (-) Light Blue