virtualbox.org

My HP Desktop has a R/W DVD. However, when I open K3B in Linux, I get a message that no Optical Device was found. I have been into Setup and tried different things, but no luck. The DVD player was working as I used it to install a Linux VM which works fine.

Your virtual machine has a virtual CD/DVD and it is independent of what your host has or has not. First of all you have to make sure that your VM has a CD/DVD "placeholder". You go to the VM Setting » Storage » Storage Tree. Make sure that there is a CD/DVD there. There is an option to use "Passthrough", i.e. use your host's physical CD/DVD. Select the CD icon on the left and click on the CD icon on the right, selecting Passthrough.