Well, i received the skeleton key and did a fuc*"* mistake… i opened the doors but retreated to continue to explore the dungeon ( Misery ). When i went back, i found out that the doors are closed and that i need to forge another key. I forged another key with the Blood of CH’THON & other ingredients but still the door won’t open. Any help guys???
You need to load a new session. Roguelike dungeons can only be opened once per session.
But there’s no rift there. I have to battle all 3 levels to arrive to the doors???
Yes, you’ll have to run through it again.
Ok i will go through it straight away. Cheers 
P.s. If you die down there, you can’t rift back. In the immortal words of Eminem, “You only get one shot, do not miss your chance to blow, this opportunity comes once in a lifetime (play session)”.
Also FYI if you’re geared well enough to do SoT you can just run past like 90% of the trash in the first 3 levels, punching only the things what get directly in your way on stairs and what. Do that and it’s like 30 seconds to the 3rd floor.
You can rift back to town to sell goods and prepare on the third floor before passing through the door, but you can’t be near it. If you’re too close to Kalderos your rift option will black out. I usually run the first three for drops, rift out, then back in and finish the last two. (Too much loot drops, don’t want to leave it on the floor)
Likewise, if you aren’t geared well enough to blow through the trash to get to the door in quickly then you might want to come back later as the mobs on the other side are much harder!!
Ok done and thanks everyone for the help. But i have another question… In these levels when you cannot rift to sell the equipment, is there a way to do so??? All this loot here and i cannot sell 
I’m currently in SUFFERING & cleared the Bone Chamber. There’s a ton of loot left.
Nope. Prioritize.