I think you better fix Black Ops 2 installation from Steam:
Go to Library > Right click Black Ops 2 > Properties > Local File > Verify integrity of game cache
If you want manually do it, copy binkw32.dll to Black Ops 2 directory. I have Steam installed in D: driver:
D:\Gamez\Steam\steamapps\common\Call of Duty Black Ops II.
If you have installed it on C: it could be here (not sure if that Steam folder is default name for it):
Win7 64-bit
C:\Program Files (x86)\Steam\steamapps\common\Call of Duty Black Ops II.
Win7 32-bit and Win XP:
C:\Program Files\Steam\steamapps\common\Call of Duty Black Ops II.
EDIT:
Fixed missing info on Steam fix section