Disc will not eject from external drive.

I have MacBook Pro 2013 using High Sierra OS and have external disc drive. I cannot get a new blank disc to eject from the drive. Eject button does not work. Now drive is not visible on desktop or disc utility or system preferences or finder or launchpad, so DO NOT now have an eject button to press. This occurred while an Apple Tech Support person was assisting me in trying to duplicate a disk. I took it to Apple Store and they cannot remove disk and just said to purchase another one. Any suggestions? Thank you.