Employment details

HI, i am working in a partnership firm right now, earlier i worked in a company, i fill my employment details with icai of my previous company, now i want to change my employment details but i do not have my experience certificate from that company or any other writter letter of that company and it its not posbile to get any letter from that co, so what should i do now to get my employment details change in icai....Please help me as soon as possible...ITS IMPORTANT....