The beat approach shall be to use your resources, rapport, goodwill, negotiation/ persuasion skills and persist and resolve the matter in your favor while you are serving your notice period. You may face such situations with future employers also. This is HR matter and you should develop basic abilities to handle these. You can seek help from elders in the family, experienced and competent well wishers, lawyer/law firm.
You can send your notice of resignation with effective date of your resignation i.e. one month from the date of notice of resignation, clearly mentioned in your notice, and quote the relevant terms and conditions mentioned in your appointment letter.
You can ask for and obtain the standing orders of the company and employee rule book, and check is it mentioned anywhere that you need to work for at least 1 year.
Have you signed any service bond?
You can not be forced to work against your wishes. Your liability is to compensate the company maximum to the amount of shortfall in notice period, or service bond (if legally enforceable)
You should complete all tasks/assignments and obtain a communication from your line management that nothing is pending to be done by you. If they do not provide you should submit a written communication, under acknowledgment, from your end with a copy to you. You should build favorable record.
You should demand in writing by a letter addressed to your appointing authority, MD, HR Head, Company Secretary, under acknowledgment, from your end with a copy to you, acknowledgment of your notice of resignation immediately, acceptance of your resignation, and to keep ready settlement of you’re a/c and payment of your dues, F&F, service certificate, reliving certificate, form 16, PF accumulation reports, PF transfer/withdrawal forms, NOC/NDC etc and to supply these to you say within 7 days. Let the company reply to your communication in writing.
Company can not block service certificate. Company can sit on reliving letter.
If nothing works you can approach o/o labor commissioner/ issue legal notice by your lawyer.