Wrongfull termination from job

Dear Sirs; I am an design engineer in mechanical with 15 yrs of experience. A US mnc in Bangalore had followed up constantly to join them and I joined them 2 yrs ago. But to my surprise I get a negative feed back from US team regarding designs sent by me. Few times I checked that and found they used my design with few changes. But I would not get any additional training and I am the only one who didn’t. Also all the office members get US visa and keep travelling I have not been considered to get a visa even. Recently I had a ligament problem and had taken a PTO But not continuously. Even then I have been in touch with office and was working on deliverable design at home and sent it to US team. The very next day they said I am fired for non delivery and inefficiency from that day. They knew about my medical condition and I might go for an operation. They are offering me one months pay. I tried to find out what went wrong and which delivery they mean as I had sent by 3 am IST and at 9.30 am I got fired with no explanation. It was really very insulting as I was the most experienced person and most of the people take help whenever they need but yes They did the job. This happened few times before and the Indians are treated very bad in India and American members get best treatment. Can I fight them in a court of law since I have not been given any reason of explanation and was refused talking to them in US. I want the other employees to benefit hence want to take the company on. Further I will find it very difficult to find a job without a job with my experience. Friends can anyone pls let me know what can I do Legally…..I am looking at discrimination to me dignity and unfair termination. Thank you all. Regards Venugopal