Form 16 not provided by employer

Hello Friends,

I had filed IT return for the assessment year 2012-13 and the filing was done based on tax deducted by my employer evidenced in salary slips.No Form -16 has been issued by my employer and neither have they deposited the deducted tax with the IT department ( no reflection in Form 26AS ).I have received a demand note from Income Tax regarding immediate payment of tax deduction that I have claimed in my return.

Kindly advise what are the options for me in such a situation.My company in question is non responsive.