First, do you have a schematic for the radio? If not, it's kinda hard to do any troubleshooting. Next, do you want to do troubleshooting? Since you have no audio from either the speaker or headphone jack, the most likely trouble is an active componet such as an integrated circuit used as the final audio amp, or an audio output transistor(s). It's possible you have a discrete componet failure such as a resistor feeding current to the active componets mentioned above, or a capacitor used for coupling audio from one stage to another. Or it could be in the audio detector circuit. If you have no noise at all, even when you turn the radio on, like a pop in the speaker or headset, then you most likely have a componet failure as indicated above and need a schematic to identify and troubleshoot the audio circuitry. If you are not familiar with troubleshooting, then it is best to get an estimate from the factory for repair. Or, if the unit is very old, it's better to invest in a new rig. Your last ditch effort is to locate someone local who fools around with electronic repair as a hobby and see if they can give you a idea of what is the best path to take. Good luck!
If you're so inclined, you could determine if the power amp (& speaker) are the problem or something before that. Just opening the scanner you might smell something burned, or see something burned.
You can get "full volume" audio "across" the volume control pot. Connect this point to an external amplifier line input (with the squelch wide open) and see what you hear. If you hear something, you know it is just the audio output stage. Note I have seen headphone jacks fail before such that they kill audio to the speaker and to any headphones connected.
If you get no audio from that point, the next circuit backwards is usually the squelch. But that does depend on the exact model, etc of your unit.