my webcam not working ubuntu20.04

Details please, e.g. make and model of the webcam, etc.

If the webcam is built into the laptop (if its a laptop, we have no idea up to now) then please give the make and model.

What is the output of:

sudo dmidecode -t 1; lsb_release -a; uname -a; lsusb

Thanks

Output of : sudo dmidecode -t 1; lsb_release -a; uname -a; lsusb
# dmidecode 3.2
Getting SMBIOS data from sysfs.
SMBIOS 3.0.0 present.

Handle 0x0001, DMI type 1, 27 bytes
System Information
 Manufacturer: LENOVO
 Product Name: 81F4
 Version: Lenovo ideapad 330S-14IKB U
 Serial Number: YD05KX2R
 UUID: 04d3b0de-2db7-2018-0520-132105000000
 Wake-up Type: Power Switch
 SKU Number: LENOVO_MT_81F4_BU_idea_FM_ideapad 330S-14IKB U
 Family: ideapad 330S-14IKB U

No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.1 LTS
Release: 20.04
Codename: focal
Linux praveen-Lenovo-ideapad-330S-14IKB-U 5.4.0-48-generic #52-Ubuntu SMP Thu Sep 10 10:58:49 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 004: ID 174f:2426 Syntek Integrated Camera
Bus 001 Device 003: ID 8087:0a2a Intel Corp.
Bus 001 Device 002: ID 046d:c534 Logitech, Inc. Unifying Receiver
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Output of : sudo dmidecode -t 1; lsb_release -a; uname -a; lsusb
# dmidecode 3.2
Getting SMBIOS data from sysfs.
SMBIOS 3.0.0 present.

Handle 0x0001, DMI type 1, 27 bytes
System Information
 Manufacturer: LENOVO
 Product Name: 81F4
 Version: Lenovo ideapad 330S-14IKB U
 Serial Number: YD05KX2R
 UUID: 04d3b0de-2db7-2018-0520-132105000000
 Wake-up Type: Power Switch
 SKU Number: LENOVO_MT_81F4_BU_idea_FM_ideapad 330S-14IKB U
 Family: ideapad 330S-14IKB U

No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.1 LTS
Release: 20.04
Codename: focal
Linux praveen-Lenovo-ideapad-330S-14IKB-U 5.4.0-48-generic #52-Ubuntu SMP Thu Sep 10 10:58:49 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 004: ID 174f:2426 Syntek Integrated Camera
Bus 001 Device 003: ID 8087:0a2a Intel Corp.
Bus 001 Device 002: ID 046d:c534 Logitech, Inc. Unifying Receiver
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

OK you have a Syntek camera with ID 174f:2426

Use the Web and search for the ID. You may find solutions

There is no luck .. still have the same issue.

I suggest that you try contacting the manufacturer and ask then about linux drivers.