Kia Troubleshooting Questions? Ask a Mechanic
If you pull all of the fuses related to the radio, play with the radio buttons after you do this. Re-install all of the fuses and see if the audio comes back. If it doesn't, it is likely that you need a radio. There is a possibility that the amp is bad, but you would need to do some further electrical diagnosis to determine that. If you are capable of doing that I could guide you. If you aren't I would recommend having a Kia dealership diagnose the issue.
There is the AMP 30A fuse, the AUDIO - 2 7.5A fuse, but also the yellow shunt with 2 fuses in it under all of the other fuses on the interior fuse panel. Pull that out as well as the other fuses. The electrical diagnosis will involve locating the amp, unplugging it and checking for voltage and ground at certain pins of the connectors so you will need a multimeter. Try the fuses again first.
I usually do for a minute or two, all while playing with the radio buttons.