So I was at the Folgunthur tomb, and I was at the first room. I saw the gate beetween the 4 pillars and I walked through it. Then I saw the chain at the left. I made a big mistake by pulling it and by going to the first room. Now I'm trapped in the very first room with 4 pillars. Basically, I killed 0 draurg in that quest. I can always exit to Skyrim but I don't want to miss that quest. I didn't get the ebony claw either. Do you know the way to pull the chain and open the gate?

You have to solve the puzzle by spinning the pillars, if I am understanding where you are stuck

See this for a walk through

http://www.uesp.net/wiki/Skyrim:Folgunthur