is this a dvd drive in a computer or in a dvd player?
is this device new, under warranty?
does the dvd disk you are using play in any other devices?
do any other dvd disks which you know work, play in this device?
does the drive spool up but then not recognize the disk or show it as blank?
or does the drive just accept the dvd then sit there without doing anything at all?
if it is a pc dvd drive do you have the wires hooked up correctly? did they come loose?
do other format disks read? (cds)
you need to determine where the problem lies by doing a few tests before we can suggest anything.