Resigned from my current company had completed my Notice period but my resignation not accepted

Dear Sir/mam, I had resigned from my current company had completed my Notice period but my resignation not accepted. And my user id is also block. Please suggest me what should i write to Hr about this.

Hi Anu,
An Employer cannot force an employee to continue her services forcibly with their concern. However you have not mentioned why they are not relieving you. In case of any pending assignments to be completed please extend your notice period and complete the same and get relieved properly. Any hasty move from your end will be benefit the employer and he will close the file employee left without information after resignation and so and so.... so talk to your HR and find out their requirement and close it.

No sir, I don't have any incomplete assingement.we have not mapped in our new branch manager. I contact to Our ARSM sir but he say contact to Branch manager but Branch Manager sir say Old employee are not mapped in my system. Please suggest me what I do. Or what should I write to H.R.

Hi Anu,
Maping or not maping is internal issue of the Company. You can write a detailed email or letter to your HR about your current situation and explain them that you have already completed your notice period and due to lack of relieving letter you were not able to join your new employer. Also try to meet your HR by person and request to expedite the process. At times lack of proper communication will result in chaos like this. Please take care.

Sir please tell me what i write to Hr. About this

Hi Anu,
I can suggest you with outline of the email. As you only know your background you need to narrate the full details in your email. Anyway please refer the following outline of email. Modify as per your requirement.
"
To
The HR Manager
__________
___________
Respected Sir
Sub : Request for relief
Ref : Name ____ Emp No___ Designation ____
My resignation letter dated_____
As you are aware, I have submitted my resignation vide my resignation letter dated___. I have completed my notice period of ____ days 0n ____as per the terms and conditions of my appointment letter dated____ . I have completed all the work assignments as assigned by my Superior.
However I am yet to receive my relieving letter due to which I am not able to join any where. When I contacted our ARSM he had advised me to contact our Branch manager. When contacted our Branch Manager he said that old employees are not mapped in his system.
Sir now I don't know how to proceed further and I am writing this email to you with a strong hope that you will be able to help me to get my relieving letter. Hope you will understand my situation and help me.
Looking forward for an positive reply from you.
Thanking you
Your faithfully
_______