How To Get Relieving Letter From Employer After Successful Relieving Process?

I resigned/relieved/laid-off. I have handed over all assets and documents on the same day. My full and final amount with 3 months notice, gratuity, and paid leaves transferred the next day to my account but HR promised to send my relieving documents also to my home the next day. But unfortunately, I have not received the documents, and after two weeks HR saying that some assets are missing under my responsibility. My reporter was looking at all the assets from the last several months. Even I don't have any idea and asked him when required and he accepted in handed over process nothing is pending. The employer sends this information to the local police also where I had a meeting and given the same explanation to them that anything missing from my relieving and processed the HR formalities, I can't provide any justification that happened in my absence. What is the option now, done many email communication to them? New employer where I selected looking for a relieving letter? What are the level options?