this is a comic book universe so anything is possible. So what do you think? In what ways could Steve Trevor be brought back, and should the writers attempt it?
Here are a few ideas.
1) Magic.
2) Flash could go back in time and grab him microseconds before his plane explodes.
3) someone looks like him from a parallel universe. (Maybe a Star Trek cross over with Chris Pine playing Captain Kirk)
4) a villain with the power of illusion impersonated him.