Did it finally start after awhile?
If yes, need to reeducate the system which disk to boot from. Go to System Preferences / Startup Disk, click on the picture of your startup volume and quit. Next time around it will know where to go.
If no, then your startup volume is toast and the bootloader can't start from it. Hold down Command-R before the startup chime to boot in Recovery Mode, then use Disk Utility to do a Repair Disk and Repair Disk Permissions on your Macintosh HD volume. Repeat if Repair errors appear. Hopefully that will cure the problem. Holler if it didn't.
Five ways to eject a stuck CD or DVD from the optical drive
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:
If this fails then try this:
Boot the computer into Single-user Mode. At the prompt enter the same command as used above. To restart the computer enter "reboot" at the prompt without quotes.