This article is From :

https://discussions.apple.com/thread/4211891?tstart=0

Ejecting the stuck disc can usually be done in one of the following ways:

1. Restart the computer and after the chime press and hold down the left mouse button until the disc ejects.

2. Press the Eject button on your keyboard.

3. Click on the Eject button in the menubar.

4. Press COMMAND-E.

5. If none of the above work try this: Open the Terminal application in your Utilities folder. At the prompt enter or paste the following:

  /usr/bin/drutil eject

If this fails then try this:

Boot the computer into . At the prompt enter the same command as used above. To restart the computer enter "reboot" at the prompt without quotes.