how can i turn "Mic Front Input" option on for alsamixer from cmd line
 

\../

What the hell is that?

As far as the question that you put into the subject line, you should be able to hit M in order to mute and unmute the mic.

I don't want to mute/unmute mic, I need to turn on 'Mic Front Input' (under the switches tab in the gui) option from command line.

If you are using alsa you can log in as root, run "alsaconf" and let the system find your sound hardware. Load the appropriate driver package and then check "alsamixer" to set the line-in level for the mic you want.
I hope this helps.

alsamixer works fine but figuring out the exact command is what I am having trouble with. the man/help pages offer some not very helpful information..

I figured out how to set the sound levels, mute and unmute:

but this one is a tough one to crack.

amixer
 

Check out /usr/bin/amixer -h

then check out
/usr/bin/amixer scontents

maybe this might work
amixer set 'Mic Select',0 'Playback' 'on';

BTW, on another note some mfgs use a facade on the front of
the box. In other words just to look good they put an input
or outlet that is non functional. So check if the wires are
connected. ;)