Someone file case against me u/s 420

This issue is rasing around 6 to 7 years back that time i am working stock broking company and one of my nri client have physical shares of shree cement that time its value around 10 lakhs.When the shares will be dematerialied and sell that shares taking permission from client that time the value is 15 lakhs.After sell that shares i asked and get permission from client that the amount will invest in other shares and i will be managing your demate account.client give me 3 years for that,In this three years i am unable to managed his account properly and i have lost all the money and client lived in dubai thats why i dont have any recording of our conversation in which he gives me permission for managing his account.In 2014 I quit that company and i told all the matters to the client but he put all the blame on me and said that i give 15 lakhs to them.Then they involves his faimily and relatives in this matters and then all of them intimidate me and froced me to give all the money that time i am very nervus and give 55000 in two instalment after that we make a legal agrement that he give 15 lakhs to me for buying property and i will give that money after two years.Now the tenure is completed and i am unable to pay it back.Now they ready to file a case against me u/s 420 now what can i do.help me out.