Recently my stock single disc cd player in a 2004 F150 Supercrew XLT has stopped working. The unit itself gets power but has no audio output. Same with the radio. It sounds like something is loose but im not too sure how all the wiring works. Can anyone help me out?

 

Check your speakers, chances are that one of the is grounded somehow, whenever 1 speaker gets a neg. signal it causes there to be no sound at all from the HU.

this could happen by:
pinched wire
damaged speaker
blown speaker
loose connection
maybe even an internal problem on your HU

If you changed your speakers it might be that one of the terminals came loose and is making contact with a ground source

The easiest way to test your speakers is to either use a test dmm or a test light at the HU harness

Wire colors for your 04 screw:
Radio 12v lt. green/purple
Radio Ground black and black/lt. green
Radio Ignition pink/black or lt. green/yellow
Radio Illumination lt. blue/red (dimmer)
Factory Amp Turn-on dk. green/purple
LF Speaker +/- orange/lt. grn - lt. blue/wht
RF Speaker +/- white/lt. grn - dk. green/org
LR Speaker +/- gray/lt. blue - tan/yellow
RR Speaker +/- orange/red - brown/pink