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 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 with this part.
AFAIK, lawyers won't go for nothing unless you have ties with them and you know them personally. So that could be two deals for them, the payment for the service and splitting of the prize.
But the latter could just be an incentive and the client was happy if the case end well.