Relieving letter

My brother passed away and father was diagnosed with cancer last stage due to which I had to leave company and I told my manager that I will resign. However, he did not let me resign and asked to wait for few days. My father's condition was getting worse day by day and my manager was not letting me resign so I left office and told my manager I cannot come to office. He told me that he will discuss my problem with HR and will ask for immediate exit. While I was busy in my father's treatment. i got to know from my colleague that he was fired as 9 people resigned and this is why he was not letting me resign. After sometime, I got a notice from HR for meeting them.I could not check 2 mails and I noticed 3rd mail and replied them that I cannot come to Gurgaon as my father was not well and there is no one who can look after him.I even called HR but they didnot respond. They did not replied on mail as well. After few months they sent me a termination letter stating that I am released from my duties. I contacted them again and sent them all the documents of my father and brother and told them that I had genuine problem and my manager did not let me resign at that time. But HR are saying that it doeS not matter Because I didnot meet them when they asked me to come to Gurgaon. I told them that it was not possible for me to come there and I tried to contact them via call no one respond. And mailed them as well, no one replied on it. Now problem is- they have given me relieving letter in which I am terminated and I cannot apply in any company due to this. They are saying they cannot do anything in this case and they will keep me terminated only. Please help me and let me know if there is anything I can do as my whole career is getting ruined due to this. My company is Capgemini. They are spoiling my career. They are saying that my manager did not inform them about my problem and this is why they cannot do anything. I have sent them all the justified documents still they are not helping me. Please suggest me what should I do? Richa Yadav