Thank you so much guys...thank you all great support.
Lenovo g50 repair time lapse 4:43
I just watched the video and tried exactly he did. Then i found unplugged speakers. i repaired my pc before my near service center i think they forgot to plug back. ♂️
Under Volume Control> Configuration you may have to play with the settings in the drop down menu.
Also your Built In Audio is off try turning it on.
How old is your laptop and what make a model number is it?
Lenovo G50 5 year old
I'd think that running Mint 20 the kernel should support a driver for your sound card.
Do you have PulseAudio in your sound settings?
IF so try controlling the sound through PulseAudio.
https://manpages.ubuntu.com/manpages/bionic/man1/pavucontrol.1.html