How to Install an Existing WOW Account on a New PCby Jacqui LaneUpdated September 22, 2017
Transferring your "World of Warcraft" account from an old computer to your new computer is not a difficult task, although it can be time-consuming. Since the game is already registered to you, you don’t need to have the original CD key or even the CDs themselves—the necessary files can be downloaded for free from the game’s website.
Insert the original "World of Warcraft" game disc into your computer.
Click "Install World of Warcraft" when prompted. Select the directory where you would like to install the game and press "Enter."
Install your expansion packs. If you have both "The Burning Crusade" and "Wrath of the Lich King," you should install them in the correct order. Insert the disc for "The Burning Crusade" into your computer and follow the installation prompts. When it completes, insert "Wrath of the Lich King" and click "Install" when prompted.
You can also download the complete game by logging into your "World of Warcraft" account and clicking "Download Client." Once the client is downloaded, double-click on the file named "Installer." Continue the installation as described in the steps. You do not need to enter the activation key at any point during installation. Just log into the game using your existing "World of Warcraft" account and it will recognize that you have a valid activation key.