It is always appropriate to discuss the matters with elders in the family, competent and experienced well wishers, lawyer/law firm before taking hasty decisions. Dealing with employer have become a game of chess and one should be patient and careful.
You are right that majority of the employees do not submit even humble objections to the wrongdoings of the employer and later either suffer financial loss or harassment.
The employee should lodge humble dissent to he wrongdoings and build record and use negotiation, persuasion, persistence skills to resolve the matter in his/her favor. One should remember the employment contract can be terminated by either party and employers are known to use tactics to protect their interest even if it requires adopting unfair tactics and may cause loss to he employee.
Do you have written record to establish that you have handed over the charge, completed the tasks on hand and submitted the company property? If you do not have you should obtain it and you should submit a written communication under acknowledgment stating you have offered to complete all formalities and cooperate with the company and as per directions/orders of Mr.............on dated............you have attended office on dated................and has completed the tasks assigned to you, handed over the charge and submitted the company property e.g.............to Mr..............to the complete satisfaction of your superiors and nothing is pending to be done by you.
Since you have resigned with immediate effect company can claim notice pay. You can demand by letter addressed to appointing authority, MD, Head-HR (followed by email) the company should supply you acknowledgment and acceptance of your resignation, settlement of your a/c and dues payable to you, F&F statement, Form 16, Pf accumulation reports/withdrawal and transfer forms, work experience certificate, NOC/NDC etc by registered/speed post so as to reach you in next say 7 days, (i.e. within 30 days from date of your resignation). If you feel you may mention that you are enclosing self addressed postage prepaid envelope with your letter. If you feel you can enclose statement of amounts payables by you to company and receivables from company along with your letter.
If the company does not respond you can issue reminder and if nothing works, you can approach the o/o Labor Commissioner/wages inspector.