I have a Dell N5010 with windows 7 home basic.Unable to use an exernal headset,the microphone is not working.
Internal mic is though working.I am having IDT HD sound drivers.
I tried to re-install the sound drivers but of no help.
Microphone is not muted anywhere.Even trying to test the microphone doesnt helps.
Does it plug in the sound jacks, or is it a USB headset?
If it is a USB set, may be a conflict of the drivers. might need to disable the on-board audio to have this work.
If it is a 3.5 mm jack, try to see if it works with a different microphone. It all could come down to a defective headset.