The only thing I can think of is to delete your entire silent hunter 5 directory in the ubisoft/steam install location and then reinstalling the game through whichever platform again.
In my experience I always had to delete every trace of the game from my computer as some mod folders and data files still lingered after clicking uninstall on steam.
I heard some people say you must restart you computer after removing and uninstalling the files but I have no idea if there is any substance to these recommendations (does it actually make a difference?)
Sorry that I cannot be more useful. This game can be troubling at times and it took me a while to get it working again after I broke it....
-Linus