Oh I can help you with that! You need to get the lockpick on the stool in the first room and go to the second locked door{its near the locked cabinet at the start} you can open that room to get a level two card, then go up to the top of the centre corridor and open the level two door there and Yuri is in that room!
I wont give any more hints(unless you ask) but once you've got a level two card and the bunny transformation you can get the level 3 card