Here's a sample of what you should see.  Difference is Line in is highlighted and not the microphone.  Record tab I was thinking of does say "Recording."  If by chance you're still not seeing the Recording tab, could you please upload a screengrab?  Thanks. [IMAGE]  
So basically I have the MT Dell optiplex 7010, and I have a headset with a mic on it. The headset plugs are split so there is one for sound and one for mic. I plug them both in the 2 ports at front (the sound and mic port) the sound works fine but for some reason the mic doesn’t work. It shows plugged in and connected so I’m not sure what is wrong 
Dell Optiplex 7010 mic not working