After installing Ubuntu 20.04 LTS I had an issue with my earphones. Initially my mic and my earphones both weren't working. But after a bit of research I was able to fix the speakers but mic is still an issue.
I determined the codec with
$ cat /proc/asound/card*/codec* | grep Codec Codec: Realtek ALC662 rev3
Then after knowing the codec of my sound card I visited the kernel documentation and picked up my model and added the following line in
options snd-hda-intel model=alc662-headset-multi
This fix seemed to work when I selected Analog Stereo Duplex(unplugged) in Pavucontrol and the audio came in speakers but mic was still dead but somehow it was able to capture all the voices coming out of speaker of headphone. I went to settings but there was no option to select input device device.
I installed a audio recorder and there I could find an option to select external mic and it worked quite well.
How to fix this problem? I am unable to access mic in any other application