My dvd palyer shows NO DISC for any disc i want to play.

the laser is probably no good or the tiny motor that spins the disc is no good.there is a clamper assembly that goes in the hole in the disc.turn it and see if it spins freely.there is a bronze bushing on the top of the motor driving it ,and a small drop of light oil on the bearing will make it work again if it is gummed up..if the motor does not get the disc speed from 250 to 600rpm,fast,the laser does generate the proper info and the computer says error.yes the motors can be replaced,but the cost is as much as a new one