Quite simply how do i unlock the secret passages to get into the leyawin castle torture chamber???

http://guides.gamepressure.com/theelderscr...uide.asp?ID=841

You can read the whole story here, for the solution.

Not much really, after you talk to the thief in prison (have a lockpick to give away and learn the countess has what you are looking for, talk to beggars and the countess personel,a woman in specific, you may need to raise her dosposition,and she tells of secrets passages in the castle.At midnight go to the cellar and look for a barel with a handle to activate the passage in it.

TA DAAAH! Passage is now opened...

Yer well id done the quest before i posted this its jst i knew about some sort of passage long before i started the quest because i was once in that room for some reason (prob sanguine shrine which i never finished), and my curiosity as to getting into the passage was reawakened

Yeah, that was the same passage. I also found it while sneaking around before I started that quest.

I have been stuck a while as well as the green quest arrow is not pointing towards the secret passage.

In the store room, on the back wall you can see a "hidden door" on the wall.
There is a lever inside a topless barrel just on the left of it: this is the lever that allows you to open the secret passage