Ubuntu 16 won't find sound hardware

I have 16.04 LTS. Sound worked until a week or two ago. Now the hardware is not recognized: in Control Center, under Sound > Hardware there is not device shown.

BACKGROUND:

Had sound for years. Perhaps two weeks ago the sound stopped working. Some googling suggested running
  rm -r ~/.config/pulse; pulseaudio -k
and rebooting. That seemed to make a difference until it didn't. Some more googling suggested adding this
  options snd-hda-intel model=auto
to the end of /etc/modprobe.d/alsa-base.conf and rebooting. Here also I thought it mattered but after a couple of days it stopped working. Now no combination of those two and rebooting seems to matter. (For rebooting, I am shutting the machine completely off and then restarting by pushing the power on button.)

NOW

The speakers are not muted. There is no hardware device shown in Control Center > Sound > Hardware.

I followed the suggestions on
  https://help.ubuntu.com/community/SoundTroubleshootingProcedure
and rebooted. They did not seem to make a change. I also gathered the information suggested there. It is below.

I would be very grateful for any suggestions.
Thanks, JIm

-------------------------------------------------------------------------

upload=true&script=true&cardinfo=
!!################################
!!ALSA Information Script v 0.4.64
!!################################

!!Script ran on: Wed Aug 14 17:56:14 UTC 2019

!!Linux Distribution
!!------------------

Ubuntu 16.04.6 LTS \n \l DISTRIB_ID=Ubuntu DISTRIB_DESCRIPTION="Ubuntu 16.04.6 LTS" NAME="Ubuntu" ID=ubuntu ID_LIKE=debian PRETTY_NAME="Ubuntu 16.04.6 LTS" HOME_URL="http://www.ubuntu.com/" SUPPORT_URL="http://help.ubuntu.com/" BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/" UBUNTU_CODENAME=xenial

!!DMI Information
!!---------------

Manufacturer: Dell Inc.
Product Name: Latitude E5470
Product Version:
Firmware Version: 1.12.6
Board Vendor: Dell Inc.
Board Name: 06DNG5

!!ACPI Device Status Information
!!---------------

/sys/bus/acpi/devices/ACPI0003:00/status 15
/sys/bus/acpi/devices/ACPI000C:00/status 15
/sys/bus/acpi/devices/DELLABC6:00/status 15
/sys/bus/acpi/devices/DELLABCE:00/status 15
/sys/bus/acpi/devices/DLLK06DE:00/status 15
/sys/bus/acpi/devices/INT33A1:00/status 15
/sys/bus/acpi/devices/INT3400:00/status 15
/sys/bus/acpi/devices/INT3403:00/status 15
/sys/bus/acpi/devices/INT3403:01/status 15
/sys/bus/acpi/devices/INT3403:02/status 15
/sys/bus/acpi/devices/INT340E:00/status 15
/sys/bus/acpi/devices/INT3F0D:00/status 15
/sys/bus/acpi/devices/LNXPOWER:00/status 1
/sys/bus/acpi/devices/LNXPOWER:01/status 1
/sys/bus/acpi/devices/LNXPOWER:02/status 1
/sys/bus/acpi/devices/PNP0103:00/status 15
/sys/bus/acpi/devices/PNP0401:00/status 13
/sys/bus/acpi/devices/PNP0C02:01/status 15
/sys/bus/acpi/devices/PNP0C02:03/status 3
/sys/bus/acpi/devices/PNP0C02:05/status 3
/sys/bus/acpi/devices/PNP0C04:00/status 31
/sys/bus/acpi/devices/PNP0C09:00/status 15
/sys/bus/acpi/devices/PNP0C0A:00/status 31
/sys/bus/acpi/devices/PNP0C0F:00/status 9
/sys/bus/acpi/devices/PNP0C0F:01/status 9
/sys/bus/acpi/devices/PNP0C0F:02/status 9
/sys/bus/acpi/devices/PNP0C0F:03/status 9
/sys/bus/acpi/devices/PNP0C0F:04/status 9
/sys/bus/acpi/devices/PNP0C0F:05/status 9
/sys/bus/acpi/devices/PNP0C0F:06/status 9
/sys/bus/acpi/devices/PNP0C0F:07/status 9
/sys/bus/acpi/devices/PNP0C31:00/status 15
/sys/bus/acpi/devices/SMO8810:00/status 15
/sys/bus/acpi/devices/device:09/status 15
/sys/bus/acpi/devices/device:62/status 15
/sys/bus/acpi/devices/device:74/status 11

!!Kernel Information
!!------------------

Kernel release: 4.15.0-58-generic
Operating System: GNU/Linux
Architecture: x86_64
Processor: x86_64
SMP Enabled: Yes

!!ALSA Version
!!------------

Driver version: k4.15.0-58-generic
Library version: 1.1.0
Utilities version: 1.1.0

!!Loaded ALSA modules
!!-------------------

!!Sound Servers on this system
!!----------------------------

Pulseaudio:
      Installed - Yes (/usr/bin/pulseaudio)
      Running - Yes

!!Soundcards recognised by ALSA
!!-----------------------------

--- no soundcards ---

!!PCI Soundcards installed in the system
!!--------------------------------------

00:1f.3 Audio device: Intel Corporation 100 Series/C230 Series Chipset Family HD Audio Controller (rev 31)

!!Advanced information - PCI Vendor/Device/Subsystem ID's
!!-------------------------------------------------------

00:1f.3 0403: 8086:a170 (rev 31)
 Subsystem: 1028:06de

!!Modprobe options (Sound related)
!!--------------------------------

snd_pcsp: index=-2
snd_usb_audio: index=-2
snd_atiixp_modem: index=-2
snd_intel8x0m: index=-2
snd_via82xx_modem: index=-2
snd_atiixp_modem: index=-2
snd_intel8x0m: index=-2
snd_via82xx_modem: index=-2
snd_usb_audio: index=-2
snd_usb_caiaq: index=-2
snd_usb_ua101: index=-2
snd_usb_us122l: index=-2
snd_usb_usx2y: index=-2
snd_cmipci: mpu_port=0x330 fm_port=0x388
snd_pcsp: index=-2
snd_usb_audio: index=-2
snd_hda_intel: model=auto
snd_hda_intel: model=generic

!!Loaded sound module options
!!---------------------------

!!ALSA Device nodes
!!-----------------

crw-rw----+ 1 root audio 116, 1 Aug 14 13:54 /dev/snd/seq
crw-rw----+ 1 root audio 116, 33 Aug 14 13:54 /dev/snd/timer

!!Aplay/Arecord output
!!--------------------

APLAY

aplay: device_list:268: no soundcards found...

ARECORD

arecord: device_list:268: no soundcards found...

!!Amixer output
!!-------------

!!Alsactl output
!!--------------

--startcollapse--
--endcollapse--

!!All Loaded Modules
!!------------------

Module
nvram
msr
ccm
rfcomm
bnep
uvcvideo
btusb
videobuf2_vmalloc
videobuf2_memops
btrtl
videobuf2_v4l2
btbcm
btintel
videobuf2_core
bluetooth
videodev
media
ecdh_generic
arc4
iwlmvm
intel_rapl
x86_pkg_temp_thermal
intel_powerclamp
mac80211
coretemp
snd_hda_intel
kvm_intel
snd_hda_codec
kvm
snd_hda_core
iwlwifi
snd_hwdep
irqbypass
crct10dif_pclmul
crc32_pclmul
ghash_clmulni_intel
snd_pcm
pcbc
dell_laptop
snd_seq_midi
snd_seq_midi_event
dell_smm_hwmon
snd_rawmidi
aesni_intel
aes_x86_64
crypto_simd
glue_helper
cryptd
dell_wmi
snd_seq
intel_cstate
intel_rapl_perf
dell_smbios
dcdbas
rtsx_pci_ms
memstick
input_leds
snd_seq_device
joydev
snd_timer
cfg80211
serio_raw
sparse_keymap
dell_wmi_descriptor
intel_wmi_thunderbolt
wmi_bmof
snd
ip6table_filter
processor_thermal_device
mei_me
soundcore
mei
shpchp
intel_pch_thermal
intel_soc_dts_iosf
ip6_tables
dell_smo8800
int3403_thermal
int3400_thermal
dell_rbtn
int340x_thermal_zone
acpi_thermal_rel
acpi_pad
mac_hid
iptable_filter
ip_tables
x_tables
parport_pc
ppdev
lp
parport
autofs4
hid_logitech_hidpp
hid_generic
hid_logitech_dj
usbhid
hid
rtsx_pci_sdmmc
i915
i2c_algo_bit
drm_kms_helper
e1000e
syscopyarea
psmouse
sysfillrect
sysimgblt
ptp
fb_sys_fops
pps_core
ahci
rtsx_pci
drm
libahci
wmi
video

!!ALSA/HDA dmesg
!!--------------

[ 0.057109] ACPI: Added _OSI(Linux-Dell-Video)
[ 0.057109] ACPI: Added _OSI(Linux-Lenovo-NV-HDMI-Audio)
[ 0.057109] ACPI: Added _OSI(Linux-HPI-Hybrid-Graphics)
--
[ 3.886870] dell_laptop: Using i8042 filter function for receiving events
[ 3.987744] snd_hda_intel 0000:00:1f.3: bound 0000:00:02.0 (ops i915_audio_component_bind_ops [i915])
[ 4.082096] ieee80211 phy0: Selected rate control algorithm 'iwl-mvm-rs'
--
[ 4.085355] iwlwifi 0000:01:00.0 wlp1s0: renamed from wlan0
[ 4.099778] snd_hda_intel 0000:00:1f.3: CORB reset timeout#1, CORBRP = 0
[ 4.101311] snd_hda_intel 0000:00:1f.3: no codecs found!
[ 4.185867] Adding 16440316k swap on /dev/sda5. Priority:-2 extents:1 across:16440316k SSFS