Why is my wrath of the lich king not completing installation

There are multiple things you can do in this situation, firstly, i would run a wow repair sometiems things just go wrong and it needs a quick fix, if this doesnt work, while you are downloading it check in the lower part of the download box keft corner it may say something about a firewall if it says, Computer seems to be behind a firewall try turning it off while you download; turning off firewall is indeed dangerous for your computer but if you do it; to keep your computer from getting infected i suggest opening no websites anything until you finish the download and turn it back on. If none of these work i suggest calling Blizzard entertainment- there number is 800-592-5499 for supoort.