After installing Linux on my new PC build, I noticed that my headphone wasn't detected as plugged in. Opening up pavucontrol, there were two ports int eh Built-in Audio Analog Stereo device (Line Out and Headphones). Line Out (Audio port on the rear I/O Shield of my computer) was always detected and could play audio, it didn't matter if I put in a speaker or a headphone. But the headphone port was stated as unplugged, even though I plugged it into the front headphone jack. What could attribute to this?
Can you plug in your headphones and open Alsa Mixer in terminal
Check if there's Headphone volume slider. If there is, set Auto-mute to 'Enabled' and change your headphone's volume.
If anyone is looking for an answer (this is the first that comes up) that alsamixer does not fix, after searching for hours and trying many solutions this one worked for me:
apt-get install alsa-tools-gui sudo hdajackretask
Then override front jack to headphones and install the boot override