Is an Employer file a case against the employee for not handovering company assets after termination

I was working with a interior design company in kolkata since August-2017, 4days ago my boss sent me a mail stating that "you has been terminated from your job due to negligence in work further he mentioned that you have to return all the assets which belongs to company including the soft copies and hard copies of the drawing file and also erase it from all personal devices otherwise i will take legal action against you". after getting this letter i replied that i will handover all the assets which belongs to company after getting my last month salary, TA & Dues for material purchase. But he is still pressuring me to return the assets and threatening that he will take contractual action against me. therefore, i need your advice on the above and please be informed that i didn't sign any contract or any other contractual documents with this company and also tell me about the design and drawings copyright laws for private sectors. I really appreciate any help you can provide.