Car radio won't work

Sounds like speaker failure or perhaps a problem with the wiring harness to the radio itself.

well a lot of times the old chevys have bad wear on there antennas near the floor or elsewhere. so best bet and probably cheaper is to by an aftermarket antenna and while your at it get a new radio with cd to test the audio in speakers with out fm/am use. aftermarket harness from circuit city or gay bestbuy are color coded to any name brand after market radios.

sounds like something is wrong with the antenna.

Definitely you will need to replace antenna coaxial cable. Few models are removeable from both ends (radio end & aerial end) most are not. Best 1 step fix: aftermarket antenna that is closest physical match to original one. (Jack. Senior tech at Fortin Auto Radio / Car Stereo Centre - Cellcom Inc.) Montreal, QC.

PS.: Oh and as littlehorn and Matt pointed out, testing the audio performance of installed OEM hardware with any known good audio source capable of "cleanly" delivering anything within the range of (R.M.S) 6 watts ~ 25 watts at decent tonal range is a very good / wise recommendation. The head unit needs to be pulled out to access aerial coax / connector in any case ...and in same location is power and audio harness, might as well test it all right there on the spot and close up when fully satisfied. ~ Cheers!

Hell... very first thing I should have replied is this. If both radio units present exact same symptoms (noise only) and all connectors are properly coupled, no visible damage to wiring, please verify if the display on the units are visible (ie: time / clock / modes / tone controls / balance / fader and radio frequency while radio function is selected, etc...) Absence of digital display on front panel is often due to absence of +12 volts on memory circuit. This will not prevent the audio section from powering up, but part of the processor circuit inside the unit will remain inoperative resulting in input signal routing failure that is internally powered from the clock/presets memory section...thus, only noise. On GM units, generally a square flat plastic connector held in back of unit with metal clip, (could be either black or white in color) that connector has only 2 wires. Grey wire is illumination/dimmer and the orange one is memory backup, it should have a continuous +12 volt supply regardless of ignition key position or power switch state. (Use test light or multimeter). No power usually due to blown fuse either under dash or under hood. If display lights up normally and clock keeps time everything power supply is normal so jump to antenna change and speaker test as previously posted by most everyone above this post. Sorry for omitting to define this basic but quite necessary FIRST check. Must be the installer persona in me that jumped over the tech and got first in line to answer. Woohoohoo!!...ciao evry1! Rock On.