CTRL+SHIFT+ESC (open Task manager)=> move to Details tab => scroll down => right click on all wow.exe => end task
do you actually have Alpha ?
or your Battle-net app is broken, YES, it doesn’t fix it by it self, you need to do it manually
You need to do only the battl-net app part, but still recommend do the 3-4 folders in WoW too
guide: