If you were just using it and it died, your on-board audio or sound cards' port has likely croaked.
In your case, pun intended, I would first unplug the power to the power supply and open the case, and see your dust situation in there, it looks like a short to me if your mic is listed as MAX constantly.
[not suggesting you go in there if not knowledgable, but if dust is obvious and thick in there, that PC is in jeopardy and sound is just the beginning]
If laptop, I'd still go in there and look the insides over, but you shouldn't.
Verify that your mic still works on something else.
If so, I would look at a 3rd party audio solution, one possibility, something like this: SYBA SY-AUD20091 Adapter - Newegg.com
If it's a deskop, http://www.newegg.com/Product/Produc...82E16829102012
is decent cheap one for replacements.
Much cheaper than paying someone like me to fix.