We're all waiting for you to name the casino. And the fact that you have asked about if it's possible that you have to work with a lawyer considers this involves a probable large amount.
Otherwise, you can talk first to that casino and settle this.
didnt knew that accusing for real requires a lawyer and we all knew that lawyer cost much . if the accused casino fights back , they can always afford to find a good lawyer so chance of winning on them is still slim . settling things first by talking to them directly is the best way to fix the issue but what if a casino is really a scam , they wont still tell the truth right ? best way to ask for other players on the site too if they experience the same thing to cut the cost .
I might be wrong but I believe It works like this in these situations:
You find a lawyer and explain the situation. If the lawyer is interested, and wins later,
you and the lawyer will split the prize. If he loses you lose nothing, but i might be wrong here.