Are you on peaceful? Can you find the spawners? If so, you're probably on peaceful.
Check if your difficulty is on peaceful.
That's really the only thing I can think of, as blazes should spawn in nether fortresses.
Blazes sometimes randomly spawn. If you still can't find them then probably try going into creative sacrificing a sword and like 5 iron and give your self your blaze rods so its fair. Or maybe even 2 diamond. That makes it fair if you don't have any spawners. Also maybe try the X-ray glitch.
Noob question, where do i find the fortress, I've had a bit of a look around but keep dying after a bit so I've been making short trips to bring back stuff.
Finding the bricks that make up Nether fortresses is very obvious, by obvious I mean stand out so blindly you cannot miss them. Sometimes they are buried, I have found completely buried fortresses before.
I would presume to say you just have to find safe ways and look around. They love to spawn on top of lava oceans.