Thanks, angel. I read a little in the post, then changed the "microphone" setting (in skype -> options -> sound devices) to "HDA Intel, ALC268 Analog (hw:0,2)" and, lo and behold, it works to a degree. The quality is lousy, but at least there's some response (I tried all other options, with no success, BTW). Strangely, though, when I try to adjust the mic's parameters (using Volume Control) I get a message "Waiting for sound system to respond", which it never does and I have to cancel. So I don't know what I've corrupted there
Rebooting doesn't solve that prob, either. Anyway, it's late now, so I'll continue tomorrow. Thanks, once again.