I have done some searches, even here on the Forum, I have not found a fix for this glitch/bug at all. I went to Riften and Brynjolf approached me and gave me the quest where you steal the ring and plant it in someone elses pocket, I completed it and he told me to go find him in the Rotway, this is where it glitches, he just stands there after the first quest is done, everytime I try to talk to him he just says "hmm..." over and over. I've ran into him near the underground bar in the Rotway, but I get the same damn reaction.

Also, I gave up after a while and decided to do the "Bring the Unusual Gem to an appraiser" quest and that D.B. is glitched out also, tells me to "Piss off" or "prove yourself to Brynjolf" WHICH I CAN'T. This is really fustrating and would be really nice if someone had some info on how to get this working.

P.S. I have tried luring him into the rotway and sheathing, he does stop attacking me only to say "hmm..." again.