Can I sue my mobile company if they do not help in deactivating my lost mobile even if my network service provider had cancelled its service?

You can sue anyone, at any time, for any reason. Unless you can show that the phone manufacturer has the ability to deactivate your phone and the responsibility to do so, though, you’re unlikely to get very far in court. And I’m not a lawyer, so if you need real legal advice, you need to consult a real lawyer.

If your service provider has cancelled the service to that phone, why are you concerned with what the phone manufacturer does? What do you expect the phone manufacturer to do?

I too have the same question as cwilbur. If service is cancelled by your “network service provider”, why would you want to sue the “mobile company”? What do you want them to do?