Sound stopped working -

[Bob Goodwin]

        Sound stopped working after I tried a USB Sound Adapter, which
        only lit its indicator leds.

        Normally the following should produce sound from the loudspeaker.
        [root at box6 bobg]# aplay /usr/share/sounds/purple/login.wav
        ALSA lib pcm_dmix.c:1018:(snd_pcm_dmix_open) unable to open slave
        aplay: main:660: audio open error: Device or resource busy

        It does not, and no sound shows on the PAVC input or output
        bars. I'm not certain of how signal moves through the sound
        circuit but it looks like it doesn't get from PA to ALSA input?

        I can feed a signal into the sound input jack and produce normal
        indications on the PAVC display and sound at the loudspeaker.

        Apparently plugging in that USB "sound adapter" switched
        something in the logic. Rebooting has not changed things? Is
        there a default conig. file somewhere?

        I've tried everything I can think of via the alsamixer display
        settings.

        Everything did work normally before this.

        Also, it would be helpful if there was a way to generate a
        continuous tone or keep aplay looping continuously when messing
        with cables under the desk, etc. I have not been able to find
        anything to do that.

        Suggestions wanted, what do I do next?

        Bob
        .