a very ambiguous question.
Unless the man knows his destination, finding an answer becomes an exercise which is non-deterministic polynomial-time hard and cannot be solved without studying the problem and the man deeper.
First of all it depends where he wants to go and how far he already progressed on his journey so far. Secondly men would never admit that they’re lost and be too embarrassed to ask for directions. Depending on his stubbornness to seek guidance this wil extend the number of roads he ends up walking considerably.
Thirdly we may be able to derive an answer based on how many roads other man with a similar background had to travel, but it will not provide us with any certainty as to the real number.
Should he be foolish enough to have left his home without a smartphone and a high quality back-up paper map (for areas with spotty cell coverage or in case he is on one of those shitty mobile data-plans from Verizon), he will clearly be leaving it all to chance.
In which case any conclusion derived might be as accurate as: he must travel as many roads as the chicken crossed. Which as we all know is 42.