No sound on radio but it shows channels. 20amp fuse blown and new on blows when inserted

How old is the battery? In general, vehicle batteries are considered 'old' after 5 years especially on bigger engines.
Using a volt meter or a multimeter set to Volts try this. With the engine off and the Keys out test the voltage directly on the battery. You should get a reading somewhere around 12.6 to 13.2 volts. Start the engine and retest the battery voltage. If the alternator is working correctly the reading should rise to somewhere around 13.6 to 14.2 volts.

blew up the huge 100amp fuse to the alt.
if new alt is born dead the fuse is blown.
or worst but lets hope just that huge fuse.
1 of these
top 2 if has 2 there is first check.
fuse 3 is for regulator,.
as you see they are ford only color coded

alt is bottom 2 wires. battery is left.

so if you charge the battery with a charger (a tool) and does the car crank and run and ok? like that then the battery is okay.
and if it ran like that did the cluster battery/charge lamp glow (err0r)?<<< please tell what the IP cluster lamp does, key on and running, thanks

all cars on earth have ALT fuses, yours has 4
count them here
1,2,3,4
the blow out for 2 reasons, ,bad alt shorts and blows the fuse, look ma' NO FIRES
or installing any ALT with battery NEG LUG, NOT REMOVED FIRST AS THE SERVICE MANUAL SHOWS
AS STEP #1


SEE LONGER ANSWER BELOW.

You have possibly melted a couple of wires together along the radio circuit. Also the radio unit itself has 1 or more protection fuses actually inside the unit that have blown, usually at back of unit in little bay near the wire clusters.
Check your relays too, a blow out through jump starting can do all sorts of little burn-outs.

Middle fuse in the fuseholder attached to the positive terminal of the battery. It is probably a blue fuse and the cap is marked ALT 100A

Usually blows because someone attached the cables the wrong way round trying to jump start (which is easy to do on the side of a country road in the dark when it's raining) or else put in a new battery and got the terminals the wrong way around (which is pretty hard to do).

Let us know if you find it. If you put a new one in and it blows again, you may have an alternator problem so don't try it again before sorting that out (may even need an alternator).

Check that power is actually getting to the radio. A cheap multimeter will do the trick. Connect the red tester to the power supply and the black to any earth (-ve). The body of the car is earthed so any bolt into the body will do.

Check that the radio doesn't have its own inline fuse which could also have blown.

It takes quite a substantial fault to blow a 20 amp fuse so take care, there may well be a dead short somewhere.

Chsnge the alternator, anything that blows a 100 amp fuse is a definate direct short to ground. Check for a loose or broken connection

yep, good sense. Lesson learned? Don't cross the wires!

sounds like you have a bad ground or a short in a wire.

Did he connect the cables wrong? I would have the alternator tested. I've seen bad alternators blow there fuses. If the cables were hooked up backwards, it may have damaged the alternator.