[mr_sir]

Originally Posted by Stiffo

yes i did actually maybe that´s it. no i didnt tried to continue in the sewers they are still locked thanks

The sewers stay locked until you talk to Dev/Null. To be honest I haven't got a clue what the problem is. I've played the game twice and haven't run into this problem in either game and by the sounds of it neither has anyone else. The only thing left that I can think of is maybe starting the whole of New York all over again (if you have a save just before the start of it) but again I'm not convinced that it will work.

Did you try uninstalling then installing again like Acleacius suggested? It could be that one of the files didn't install properly. You don't need to lose your saved game as you can just make a backup of your save folder before doing this.