What can I do if a company terminated me without any appropriate reaso

I work as a senor manager in one of the MNCs based out of Bangalore. I have raised a mental harassment complaint against my line manager with all necessary documents and no action was taken against him. During the performance review cycle, my manager has rated me underperformer for which i did not agree and sent a legal notice explaining my situation and sequence of events. I had a call with my skip manager HR and legal team and post that they sent me an extremely long email saying I was not doing anything I was not doing basic responsibility as manager completely defaming me in an email and told me that this is interim response to my legal notice and after a week I countered all questions with email proof and policies and procedures I copied very senior level people including the CEO in the email response and immediately the next day I was terminated with the reason provided in the Termination letter as Misconduct and willful obstinacy violation of employee contract.