About 6 months ago the sound systemin the car.

Hi about 6 months ago the sound systemin the car went from making little noise to none. I read forums saying it was probably a bad amplifier. I replaced the amp and had it programmed by the bmw dealership which was about an 8 hour drive from my hometown. They thought that would fix the no noise problem but it did not. They said they would charge me another 2 hours worth of work at the rate of 120 and I said no thanks, because they had no idea where to even start looking for the problem other then saying it might be a lose wire or bad wiring connection. Anyway long story short, the radio still does not work. The stereo head unit displays all the right pictures and all the buttons work, but no sound. Also the steering wheel buttons work as well. So far I have spent a great deal of money on this issue only to come up with zero solutions and no working radio. Could it be the radio head unit has gone bad somehow, even though everything seems to be working besides the sound? Is it a blown fuse, although I have checked a lot of them? I do not know what to do. Should I just spend more money and buy a used head unit? Would I have to bring to the dealership to get it programmed for another 260 dollars? I am very frustrated and need any and all suggestions and help. Please and thank you.