Can a case be filed against a company if terminated without any reason

Dear Sir/ Ma'am, I was working with an Not-for-Profit organization. Recently I was asked to resign without any valid reason. Refusing to do so, the organization paid me agreed months of salary, without any valid reason they terminated me. My appointment letter clearly said the company can terminate me on the following points: "(1) Gross Misconduct, (2) Negligence, (3) Breach of Confidentiality, (4) late attendance or absence (5) Conduct disloyal to or against the interest of organization (6) Breach of confidentiality - divulging by publication, speech or prepared statements or any other method to third party any information received/ generated during the appointment period with regards to confidentiality affairs of the organization." In my termination letter, none of the above points are mentioned - and rightly so, because I have not done any of the above. The termination letter just says, I am terminated - NO REASON is mentioned. Can I file a case against the organization.