Magic Iso and some other similar applications will take over the DVD drive, they want to act as an all encompassing virtual DVD drive. Which in my opinion sucks badly.

So when I need to use Magic ISO I install it, do what I need and remove it.

To get your DVD drive back you can go to your system manufacturer, like Dell or HP and download the drivers for it again. The system will act like it is non existent, but if you run the drivers and do a hardware scan in most cases it will pick back up and start working again.

Why they do this by design is anyone's guess, but since they are free, they probably put some disclaimer in the small print.

Hope this helps, I've had to "recover" my drives a few times through out the years.