The next step would be to launch the Disk Utility application located in the Applications/Utilities folder, click on the optical drive (called SuperDrive in Disk Utility), and then click on the eject button to see if you can get the drive to perform an eject cycle to reset the drive. You've already tried power cycling your system which didn't resolve the issue. If the optical drive is visible then the system is communicating with the drive. If no info is presented then this would indicate that the optical drive is offline, disconnected, or has some sort of issue. On the left hand column in the Hardware section click on the 'Disc Burning' section and report what information shows up. Since you are running Lion you'll then click on the Ssytem Report option which should bring up a window listing the features of your system.
Pull down the Apple Menu and select 'About This Mac', then click on the 'More Info' button.
