Upgrade from 18.04 to 20.04 and lost all sound

[MR ZenWiz]

On Sat, Nov 14, 2020 at 6:34 PM MR ZenWiz <mrzenwiz at gmail.com> wrote:
>
> I just finished upgrading Xubuntu 18.04 to 20.04 and all system sound
> is gone.  According to pavucontrol, I only have Dummy Output and HDMI
> (which is not connected and reports as unplugged).
>
> My speakers are not detected, nor is the built in sound - speakers and
> microphone.
>
> I also keep getting a "System problem is reported" and I send the
> problem report, but I have no idea what it is.
>
> Where do I look first?
>
> I cannot do without sound on this laptop (HP 8740w).  It was working
> perfectly before the upgrade.
>
Here's what lspci shows for audio - AFAICT there is no real HDMI
device on the machine:

19:45 [admar at marHP8740w:~] $ lspci | grep -i audio
00:1b.0 Audio device: Intel Corporation 5 Series/3400 Series Chipset
High Definition Audio (rev 06)
01:00.1 Audio device: NVIDIA Corporation GK106 HDMI Audio Controller (rev a1)

There's also this, which I'm not sure what to make of:

19:47 [admar at marHP8740w:~] $ dmesg | grep -i audio
[    0.144386] ACPI: Added _OSI(Linux-Lenovo-NV-HDMI-Audio)
[   19.330480] snd_hda_intel 0000:01:00.1: Handle vga_switcheroo audio client
[   19.367277] snd_hda_codec_idt hdaudioC0D0: autoconfig for
92HD75B3X5: line_outs=1 (0xd/0x0/0x0/0x0/0x0) type:speaker
[   19.367281] snd_hda_codec_idt hdaudioC0D0:    speaker_outs=0
(0x0/0x0/0x0/0x0/0x0)
[   19.367284] snd_hda_codec_idt hdaudioC0D0:    hp_outs=2 (0xf/0xa/0x0/0x0/0x0)
[   19.367286] snd_hda_codec_idt hdaudioC0D0:    mono: mono_out=0x0
[   19.367288] snd_hda_codec_idt hdaudioC0D0:    inputs:
[   19.367291] snd_hda_codec_idt hdaudioC0D0:      Internal Mic=0xc
[   19.367293] snd_hda_codec_idt hdaudioC0D0:      Mic=0xb
[   19.367296] snd_hda_codec_idt hdaudioC0D0:      Line=0xe

sudo lshw -c audio produces nothing.

Any other suggestions?

Thanks.

Mark