microphone problem mic is rear mic and when i rebooted after repair wont work
 

I have a dell 5100 and i bought a simple mic from store

its just got an on and off button, it did work fine,
i usse it to talk on messenger. Then I had to unplug all
to take my cp in for repair and when i put it all back, the mic does not work???? Have tried the control panel under speech and audio and no results.

alsamixer
 

Go into the commandline, and run alsamixer. Scroll to the right until you reach mic, and makesure it's not muted and the volumes up (m mutes/unmutes), make sure 'mic boost' is on, and finally look at 'mic select' and make sure you've selected the correct mic(Mic1 is usually for the back plug and Mic2 would be for a front plug if you have one)

Thank you for your reply, but what is 'Alsamixer'???. Never
heard of it before? Ann