You've stumbled upon an old problem in philosophy, The Paradox of Inquiry, first formulated in Plato's Meno.
The problem can be reformulated as follows:
Either you know the answer to a question, or you don't. If you do, then there is no point searching for it. If you don't, then you will not know what to search for.
The short answer is that you can still recognize a correct answer, even if you don't know what you're looking for beforehand. (Simple example: you don't know what the prime factors of a given number are. You try some combinations and eventually you recognize the correct answer simply by multiplication.)
A more recent version of the problem is Moore's Paradox of Analysis.
