I suggest the following solution:

1) type on a terminal the command dmesg
2) you will see a lot of information written on screen but somewhere in that apparent chaos you will a reference to your CD/DVD drive. In my case is:

scsi0 : SCSI host adapter emulation for IDE ATAPI devices
Vendor: TOSHIBA Model: DVD-ROM SD-C2302 Rev: 1713
Type: CD-ROM ANSI SCSI revision: 02
Attached scsi CD-ROM sr0 at scsi0, channel 0, id 0, lun 0
sr0: scsi3-mmc drive: 24x/24x cd/rw xa/form2 cdda tray

The important fact is that it says to me that my DVD is a sr0 device, so now I can mount it as

sudo mount /dev/sr0

I hope it can help