Company is stopping my FnF

I worked in an organization for 7 years. Later, I got a better opportunity so I left it after serving a 2 months notice period. Within a week from last working day, I got a mail from HR along with FNF form which I need to filled and revert, so I did same and sent back to them. After everything, I was expecting to receive my 7 years gratuity, 52 days EL balance & 9 days working salary of last month which supposed to be released in FNF. But, nothing was released and communicated, when 2 months going to be complete I contacted HR and asked about my FNF, she said that my manager sent an mail saying that I have erased my mail and deleted some IMP software, so she suggested to speak with my Manager then only they can release my FNF. I was shocked by knowing this false statement, I actually just deleted my mails which isn't intentionally. And, those were related to personal in nature like salary slips, appraisal letters, loan statements, credit card bills, etc. I was in IT Support department, not in the production department which could contains Client and other IMP communications, so my mails weren't important. Regarding Software, nothing was deleted and I also confirmed the same with my colleague, he said they have everything and nothing is missing. I emailed my Manger, keeping HR in loop, explained everything and asked for the screenshot or logs where it can be proofed that I have deleted the software or imp data, also told them that I have contacted the colleagues and they have confirmed that everything is with them and nothing is required from my side, even my help to lookout for anything. But, they aren't replying my mail. They even not communicated me for stopping my FNF, or I wasn't contacted by anyone for software or help if they required anything from my side. Actually, My manager was arrogant, in exist form I just wrote few negative points for him where the supervisor review was written. Now, he's just showing me power by making a point of nonsense and stopping my FNF by mailing HR and Compliance Head. Please confirm what should I do to get my FNF amount and experience letter. I have served my notice period and followed things. Also, please let me know that how much time does your suggested way will take.