Being threatened harassed by my last company Accentus Consulting

Dear Sir I am Ranadeb Roy, son of Mr. Ramkrishna Roy, address Garia, Tentulberia, Madhya Para, Kolkata – 700084. This is to inform you that I am being threatened in various ways by my ex-employer Accentus Consulting Pvt Ltd, P-1 Taratala Road, Webel HRDC, Room -5, Kolkata – 700088. I submitted my resignation on 2nd of March 2016 at Accentus Consulting Pvt Ltd and after completion of the due notice period, I have been released by the company on 31st March 2016 along with proper documents without any difficulty. However, after months of my release from the company, I have been receiving threatening emails from the ex-employer with allegations such as (a) Unauthorized transfer of company confidential data (b) Negligence at work (c) Suppression of facts (d) Derogating Company's and Mr. Partha Mitra's (Company Director) reputation and self-respect . Recently they are sending lawyer letter with threatening. After several explanations from my end to the company to clarify my honesty, my family and I feel threatened and falsely accused leading to insecurity and depression. I am here to file a Complaint against this mental and financial harassment. Please help me about this.