I agree - don't do a reset just yet. Welcome to the forum, btw!
A lot of the times that this happens, someone has toggled the selection that chooses if an input should use an HDMI, digital, or analog connection for the audio input. The default is often "Auto" select, but many receivers let you manually toggle between them. I didn't see that option when skimming the Onkyo manual, but it might be the cause.
I think that you're saying that you lost audio from the Directv receiver and not the Samsung TV. If so, is your Directv receiver connected to your receiver (probably over HDMI)?