This may not be a hackers job and you can possibly be scammed as well, anyways so the solution to your problem would be to "request your data" to discord which takes a couple days to arrive and then look for the servers messages, this works flawlessly for DMs and also for servers but I'm not sure how many of the messages you can view and how limited you are, by limited i mean you may only be able to see the messages you previously sent into the server, so only the messages you sent may display. Good luck