1 month salary,releieving letter witheld

I was employed with a school in Faridabad as a teacher since december 2012.I resigned on 24.02.15 on personal emergency grounds and on 21 march i reminded them once gain that i would not be coming from 23/3/15 onwards but if the school needed me i was more than happy to come on parent teacher meeting or the annual function adjusting 1 or 2 days in between.I was insulted and told by the principal that "I will not let you go till i get another teacher and will not give you the salary also you do what you want to do".Although the new teacher had already been appointed they refuse to do the needful.I contacted the principal once again on 22nd and requested him to at least release my relieving letter if they were not giving my salary.He called me to school on 24th on the pretext of giving my relieving letter and made me hand over all the official document as the procedure and then insulted me " tumahari jaisi sanki ladies ko pata nahin hota kya karna hai!I will not give salary or relieving letter till i do not get a teacher "I told him that already the teacher is working in place of me and have given my 1 months notice as mentioned in the appointment letter.His reply was that was that "madam aise nahin,aapke notice dene se kya hota hai,school ko jab lagega teacher aa gaye hai tab dekehenge."They have not even given me my resignation letter copy.After this i decided to send a registered post and a email stating all the facts and telling him to relieve me asap.Please help me as i do not know what i should do.and how much money is involved if i go legal.This principal has got got political contacts.