Appointment cancelled because of age limit issues

I was appointed as a teacher in 1998. In an advertisement published in the news paper, the school wanted 2 teachers for a specific subject & one teacher for another subject. After the interview the school management selected & appointed the two teachers for one post. A complaint was launched against one of the teacher and the education officer cancelled my appointment & the management terminated me. My application on the basis of age limit in comparison to other candidates was rejected. I want to file a case against them. How should I proceed?