Hi ya. I've just tried to log onto WoW and nothing is working

I am using an iMac running Lion OS. I played WoW last night and stopped playing and closed down as usual, no problem at all.
Today, i click the WoW icon on my desktop, it flashes, there is a small amount of hard disk activity and then it stops, nothing else happens.

I wasn't too worried, thinking I would just reinstall the game from the original DVD but when I put the DVD in, the iMac won't read, so now I'm really stuck.

I've never had any problems like this before with any patches and everything else on the computer is working fine.
Many thanks in advance...