need help recovering old messages for receipts/evidence/proof?? any help??

I NEED HELP! Okay. So i’ve been trying to compile evidence against my old abuser and his girlfriend AND his friends for enabling the abuse.. 

I have majority of receipts i need, although i cannot get through instagram for the life of me and tragically thats one of the MOST IMPORTANT pieces of info i need. 

my current situation is that we had a huge argument over text and after that i was blocked. That whole situation was really a blur to me and i think i ended up deleting the conversation from my inbox. I’m not sure if it completely deleted, but it was only a week ago and i’m pretty sure i still have 30 days to recover it. I’ve done multiple data exports but to no avail it won’t show me any of the messages between me and her. 

If any tech nerds know how to help me please do!!!!!!