Try cleaning the CD. if that doesn't work World of Warcraft gives you a chance to download the full client for free (requires a World of Warcraft Account). Also, check if you have enough space on your hard drive.
If you can not use CD's in your computer, then you can download the game from the official website and install it that way.
Torrent it
Warcraft 3 was recently patched to no longer require the CD to start. World of Warcraft as well as The Burning Crusade and Wrath of the Lich King have never required a CD to start. If earlier versions of Warcraft have not been patched to no longer require the CD, you can download a disc imaging program such as Deamon Tools Lite, create a virtual image of your CD, and "mount" the image to run the game, instead of using the CD.
Could be a faulty disk, but don't worry you can download it using the attached link :)
Just Search in YOUJIZZ.COM
Yes, it's $15 a month.
Blizzard offers a free download for it, if you have the CD-Key
If you already have a valid serial number you can add it to a battle.net account and download it there :)
The World of Warcraft game is only online but you can get the Warcraft games themselves which can be played off line.
When bought online you must download and patch the entire game from the website. Buying the CD gives you the install CD's which saves time downloading. You will still need to patch. That is the only difference.
Usually on the back of the CD envelope :)
Yes, that is possible. If you want to reinstall it from scratch, you can do it from the original CD or download you had, or you can log in to your battle.net account, click on your World of Warcraft game and choose "install client". You will then download and install the game and all expansions linked to your account. You can also copy the installation from another PC (using CD, USB stick or external hard drive) and run WoW after it has been copied to your PC.