For the last 2 years, sent .4 BTC to satoshi dice betting address before they disabled it. They never returned it. I've tried contacting them many time. I will probably never see this money again.
If the site that you are mentioning already closed then there's no chance to recover those btc that you send to their wallets, no one will
assist you, you don't have any choice but to accept that mistake and move on, it's stressful to remember those huge amount of money
but again if the site that you are referring was closed for business nothing left for you but to accept the reality. That's why is always better
to play with reputable gambling house as chances of being closed is smaller than those who are not fully established.