Cheque Bounce Case where I was asked forcefully asked to sign a cheque

Hi! Tech Mahindra asked me to sign a cheque to recover money that they were paying me salary of 3 months. Even though I stopped working with them since Oct 2015. They have shown me present in thier system and paid salary of 3 months. I asked my TL how come I am getting paid even though I am not working. He told me he was doing a favour as I am going through a difficult time and he wanted to become a Manager. So he had to show me present. It was a win win situation for both of us. Later the HR came to my house and asked me to join the Company and meanwhile asked me to sign an expired cheque. I got scared and signed the cheque. Now they have a case against me regarding Instrstrumental Negotiable Act. It's injustice, kindly advise. The case is been going on since 2015.