Regarding Rejection of Resignation post approval because of Disciplinary enquiry

Dear Sir/Madam, I am employed with India’s one of the reputed Bank as lower level manager, I resigned from my duties and was serving notice period of 90 days, same was approved by competent authority of the bank, after 80 days of notice period, as directed by mails I submitted company laptop and ID Card to concerned department and as per Bank’s separation policy I took leave of 7 days and I was supposed to resume on my Last working day, after submitting laptop and ID card I received a mail on next day that due to ongoing inquiry on disciplinary ground your resignation had been withdrawn, is this legal? I mail to HR and investigation team that I am leaving as on my approved last working day and ready to cooperate you in your investigation and you can access me through any mode and provided personal mail, mobile and address and ready to meet face to face as well. 1. Can Bank Terminate me? 2. Can they stop me such like that without intimate me about enquiry cause? 3. What if I join another organisation basis resignation approval? 4. I am eligible to receive Relieving letter? 5. Can they enquire where I was neither initiator nor approving authority?