i wanted to buy the house in windhelm but i cant start the blood on the ice quest.

was there a fix for this bug included with dawnguard?

DLCs don't include bug fixes, only official updates do. Blood on the Ice was already patched previous to the DLC, try the UESP page on it?

Blood on the Ice has already been patched. However, if your character already triggered the beginning of the quest and you missed it, then you will have to wait until your next character to be able to do the quest.

The bug was from the trigger for the quest being so far from the city that you would start the quest without even entering the city, then miss the quest because you were not around for the first events.

Since this is off topic to Dawngaurd, I will close this thread.