1. Build irrefutable evidence of being forced to write your resignation (audio/visual/witnesses/minutes) etc. The Employee's/Trade Unions leaders e.g. CITU/INTUC/AITUC etc and various forums/unions of Teachers can be your representative and witness.
2. The State Education Act, and affiliating Univ. lays down service conditions, Conduct and Discipline Rules etc. Download these.
3. Once you have the evidence you can escalalte to 1st then next levles of heirarchy in your Instt. and take it further.
4. Not assigning any duty may not bother you much as it is aimed to preturb you and coerce you to commit some error and separate.
5. Non Payment of salary is breach and can be termed offensive.
You may write to Principle (under proepr acknowledgment and with a copy to you) and request to supply you the reasons for non payment.
6. Since you are being forced/coerced you can approach court of law.
7. If there are other adverse situations then you may contemplate to approach police/women cell.
8. Firm up another venture ASAP.
9. You can also discuss the matter in person with an able Labor Law Consultant/Service maters lawyer and show all documnets pertaining to appointment, service conditions, Conduct and Discipline Rules etc and proceed further under expert advise of your lawyer.