Hi there , 
I was doing Keldeo's quest and done all right till i reached that part of fighting with " Forest MAster " but i didnt win him at 1st try cause wasnt ready , so when i tried again 
The sign is not delivering me to " Forest Dungeon Boss room " so i can fight him again & i got no idea what to do nxt ?! That part exactly in the screen shot im stuck at .

You will have to find another way to get access to the Forest Master Room now. There is a hint on the stone which is right at the entrance of the Forest Area on how you can get back now.

You pretty much have to find another loaction you have to interact with, I have seen the mushrooms on the tree stump work for some people but it could be another loaction as well from what I know.

thanks man , i found it 

Locked as resolved.