FIRST - Delete your wow folder ( just do it cause its useles and it might cause many problems )
SECOND - Download Icecold wow, put it in an empty folder on your desktop
THIRD - Sign in ( press ''ok'' in every single window that pops up, and wait a few minutes, especially when the screen goes black, this will take about 4-5 minutes, so just wait till you get to the loggin screen )
FOURTH!!!!!! - SIGN IN USING YOUR ACCOUNT NAME IN THIS SITE, NOT YOUR EMAIL, BECAUSE IF YOU HAVE A WOW ACCOUNT ALREADY, IT WILL TRY TO LOOK FOR THE BLIZZARD ACCOUNT WITH THE SAME EMAIL AND IT WONT LET YOU ENTER
In all cases try not to open the wow updater ( in case you havent deleted your wow directory file ) because it will update your files to Pandaria.
Vordnox's post in Need help on what i need to download pre patch here was marked as the answer