iMac no longer recognized my internal and external cd,dvd burner
There was a past discussion on the problem stated above, just wanted to add my solution to this problem as it just happened to me on this date. I tried all the past suggestions with no luck so here was my fix and it worked.
1 Shut down the computer and unplug it. I waited about one minute.
2 Plug it back in and hit the power button.
3 Before the grey screen shows up press and hold Command, Option, P, R, until the computer finishes loading.
4 A menu should come up giving you 4 options to choose from.
5 I choose re-install OS X and let it run to completion.
6 Both burners work and no problems with any of the other programs and applications.
Good luck with yours
iMac (21.5-inch Late 2009)