My Radio doesn't have sound but all the other functions work. What is the problem?

Eight year old car radio failed. After checking fuses and obvious stuff, get an aftermarket radio. The last two used cars I owned had aftermarket radios. Asian car radios with good names which people used to talk about in the old glory days of car radios. Way too complicated to do anything with while driving. Tiny little buttons which had a lot of functions, lots of bands, AM, FM and even Long Wave. The one I have now even has a wave display on the station display, highs, lows, etc. Maybe a passanger high on pot might be facinated watching it at night. Doesn't serve any other purpose.

Isn’t sound the only real function it has?

Hear static? Check antenna connection. No sound at all? Internal problem.

probably wiring that goes to speaker or need to replace speaker

Could be a number of things.

Most car radios have a connector at the back that connects to a cable for the speakers - a different connector than the one for power.  That cable could have come unplugged.

There is also usually a fuse on the output side of the radio - again, not the same as the fuse on the power.

The amplifier in your radio could simply have died.

There were apparently thirteen different factory radios offered in that year's Challenger, depending on the trim level.  The correct fix would depend on which one you have.

does your car have a separate amp ??  maybe IT blew a fuse ???