This guide is for those who didnt installed WoW and just copied the game files:
1. Go to START --> RUN type in REGEDIT
2. Registry Editor appears, click on HKEY_LOCAL_MACHINE --> SOFTWARE --> BLIZZARD ENTERTAINMENT --> WORLD OF WARCRAFT
3. Make sure that the UninstallPath, InstallPath, and GamePath are exactly like these.
UninstallPath = C:\Program Files\Common Files\Blizzard Entertainment\World of Warcraft\Uninstall.exe
InstallPath = C:\Program Files\World of Warcraft
GamePath = C:\Program Files\World of Warcraft\WoW.exe
If doesnt exist right click on the white box --> New and then choose String Value and do 3 string like this:
UninstallPath = C:\Program Files\Common Files\Blizzard Entertainment\World of Warcraft\Uninstall.exe
InstallPath = C:\Program Files\World of Warcraft
GamePath = C:\Program Files\World of Warcraft\WoW.exe