Following a blog, I created a contract using this code: https://pastebin.com/WAaLCGxW Now, I don't know what I did, but all the ETH I sent to the contract ended up through "internal transactions" in another address from which I can't retrieve them. The address where they ended up is this:
0x78Ba3Cd47408E6C82a29d6AD9961a40e0E62a38d.
Can someone help me?