recover my messenger

I had a conversation on messenger with a person who wanted to buy my old IPhone. That person then fooled me completely. He/she kicked me out from messenger and robbed my bank account. I have got my messenger bsck and changed password but this person have erased our conversation. There has to be a way for me to recover that data from my iPhone I used when I had my conversation!

can anyone help me and tell me how to recover this conversation from my iphone?

I was in contact with fb and got the files from them but they were erased. But that data must still be able to find in my memory on my iPhone?

plz help me to solve this.