Not paying gratuity

Dear Sir/Maam I worked for a company from Oct 2007 to May 2015, This was based out of USA and had operations in Bangalore Chennai & Coimbatore. The company ceased operations in May 2015. I have not been paid the gratuity amount. When I asked them they told me to contact the guy in USA who is in litigation with Microsoft. As expected I couldnt contact him. All the people from the old company are working in a new concern, along with the said man from US, they operate similar businesses under a different name. All the heads of dept like finance HR and ADMIN are the same people. Is it possible to get my gratuity amount from these guys? First of all they are pretty slimy characters. They dont respond to emails. The only time they responded was to tell me to contact a guy in the US who I have never met. Can I proceeded legally against the people who signed my original letter and are very much part of the new concern. I would like to know what the legal stand is. And at this point it is worth mentioning that they did not pay salaries to hundreds of employees when they shut down. Is it worthwhile for me to proceed? Thanks and Regards Deepak S