You could have a play around with sound settings in alsamixer to see if any input/output channels are muted or set low. Also experiment with [Loopback] and [Auto-Mute] channel settings to see if any effect.
To open alsamixer start a terminal session and type alsamixer
Hit [F5] to view "All" channels.
Good luck, sound issues are sometimes hit-and-miss i.e. not straightforward and logical.