HR is saying that your relieving date has passed and now you have to file a fresh resignation

I am currently working in PSU govt. I have given my resignation letter earlier in March and was serving a 3 months notice period. After 20 days, I left the company and later applied for leaves for one month for personal reason and but returned after 5 months, to serve the remaining notice period. Now HR is saying that your relieving date has passed and now you have to file a fresh resignation and serve again 3 months. Is the first resignation relapse a thing? How to proceed?

Once resignation is submitted, unless it is rejected the same is final and binding. The resignation cannot lapse by itself. Since you have not withdrawn resignation and did not show any intention to continue in service, your resignation is final and enforced. In deed the notice period being over, you need not serve the remaining notice period and you are deemed to have been relieved at the end of third month. After five months of your resignation now there cannot be a fresh resignation and you should insist on being issued relieving order and made full and final settlement.

Dear Bablu S
Resignation once submitted it cannot be replaced or lapse untill the resignee withdraws his resignation. In your case if your leaves during notice period were approved than you are only due for full and final settlement with adjustment of notice period not served.
There is no law which can be enforced on you to serve your notice again.