Well, before the big bang, there had to be some environment that was such that a big bang could occur. (Just as, before the computer was turned on, there had to be a computer there to turn on.)

The question may be unanswerable from the information available in this universe (or, in the analogy, within the computer), but we know that there had to be something there.

Probably not a good analogy, since generally there’s an RTC running even if the computer is off. ;)