I can not use any program like voice chat etc as my mic doesnot work. I
checked the mic with my laptop, it works, but doesn't with my PC(Win XP
Prof).

This is what I see...
In the recording volume control, I see 'Stereo Mix' selected. I click
on Mic check box or Aux, or CD Player check box to select those, but
nothing happens.

No matter what I click, the stereo mix is selected. I tried recording a
online radio station and it records it.

But no input from the mic.

I assembled the PC myself, can not go to any shop for help. Can someone
help me here???

Thanks,
Rohit