How about "Eu perdi o meu dinheiro todo"? is this correct?
Yes, it's okay for me.
Is it correct to write it without "o": Eu perdi todo meu dinheiro
Why not "Eu perdi todo do meu dinheiro?"
Does not sound good. There is no noun in the sentence that asks the preposition "de". It's as if something is missing. One solution would be: "Eu perdi toda a parte Do meu dinheiro" (I lost all part of my money).