To actually retrieve the computation they embodied? That which made them, well, them?

My personal guess is that, barring the possibility of "it turns out something like time travel is possible after all", and even then, the trickiness of somehow reaching back to before the machine was built, or some other improbable major physics revolution that would let us retrieve information from the past, well, sadly, I'd have to guess no.

Of course, I'd be ecstatic if it turned out there was a way. I'm just not expecting it. :(