Comment 14 for bug 1359803

Same issue, fabianbur's fix didn't work for me.

Lenovo Ideapad 305 15IBD
Windows 7 and Ubuntu 16.04 dual boot.

This day that I'm posting this is the first time I've encountered this issue, and it's really annoying. Was working fine until now, the only thing I've modified and could have triggered this to happen, was enabling the echo-cancellation in PulseAudio, as seen here: https://askubuntu.com/questions/18958/realtime-noise-removal-with-pulseaudio

Otherwise I have the same experience as Denilson Sá (denilsonsa) above, alsamixer works fine, but only 'Capture' and 'Internal mic boost' comes up as input, regardless of jack plugged in or not.