I'm stuck into the middle of the riatavin quest after saved the city from the pirate attack, I've been dragged to the government district,but no thief later just give me the location of the forest of Mir, it all just go back to normal status!!

I had that problem, when I was playing it. Summon him in with the console - TDD isn't installed now, so I can't find the code, but use Shadow Keeper.

TDD is absolutely riddled with bugs. You will find many annoying things like that while playing through it.

idd it is riddled with bugs, even with the patches and so it is still a bit moody, I gave up on it after about 2 hours gaming.