If gst is not paid for 2 or 3 months. i need to know the legal ways to solve the issue.

There is no such procedure of collecting GST as trustee, misappropriating such amount and then saying cannot return and this is Mallaya style of misappropriation.  It is not the payer that has to initiate legal remedy, it is left to Govt to proceed against such persons legally for misappropriation including cancellation of such number and criminal action.  You can help your friend and save him from the troubles as now Govt has released strict directives against such evaders.

Sir, How are you? I rechecked with my friend as per your humble and professional reply.. He said that he has taken the new GST and due to unavoidable situation he couldn't carry any business or projects revenues for his company. So, he is doing NIL Filing through one of his known person(X), who was taking care of the documentation works. Now, that person(X) did the NIL filing for the first month ( Not produced the paid receipt till now) and consectively three (3) months, he has not done the NIL filing. When my friend ask for the NIL filing receipts to the person ( X), he is relating to a unknown CA ( Charted Accountant). But when my friend approached this unknown CA, the Charted Accountant is unaware of the NIL filing details and also about the person ( X). Now, the Person ( X) claiming Rs. 7,900 ( Not revealing the reason for his claim) to my friend without any proof of document and also not revealing the user name and password of the GST. My friend would like to know how to recover his user name & password to know the status of his GST. Please kindly advise us and request you to forward your mobile number and email address for further converstation. Thank you very much for your dedicated service.

The simple way is filing RTI Application before authority and seeking confirmation and then filing a complaint against such fake persons to GST Authorities.  There should be some proof for such payment.  You can also advise your friend to file a complaint before consumer forum for deficiency of services by that professional and let your friend seek return and huge compensation for deficiency of services and such harassment.  He need not incur single rupee for filing consumer complaint, but before that your friend should issue a notice demanding for such refund or seeking receipts.