Do you mean the dvd drive, or a particular disc?
If you want to know if the dvd drive is working outside of the operating system, put in a bootable dvd disc, like an operating system disc or a recovery disc. Then reboot the computer and see if the drive will read the disc before starting the operating system that is on your hard drive. The bios of the computer will need to be set to boot from the optical drive first, not the hard drive first. Read the manual of your computer to find out how to get into the bios and set the boot order.
Once you've established that the drive is working normally and doesn't have a physical problem, you can start Windows (or whatever operating system you are using) and test it there. Put a dvd with data in the drive. Go to My Computer, right click on the drive and hit Explore to examine the contents of the disc. If the contents show up, the drive is reading it ok.