Not sure this helps, but if the address you used(12ngg3CB9VDvkbFDx7JKY92i9kYgDmiEaj) was a one-time address from coinbase. Then coinbase would have the would have the private key to address (12ngg3CB9VDvkbFDx7JKY92i9kYgDmiEaj), depending on their program, they should be able to sweep it again into your account.