My dvd player won't play dvd

SOURCE: Sony DVP-NS57P all region

Try this,
1) Plug the DVD Power Cord to the wall jack, but DO NOT Turn On the player;
2) With the Remote Control, press: Display, Top Menu, Clear and Power;
3) It will enter in the Service Mode;
4) Choose option 2 and then 4;
5) It will ask for an Input Code and Current Code (its 5 spaces), press 1245 and then Zero;
6) Leave all Zero erasing 1245, and on the bottom field all Zero too, then press Enter;
7) So the DVD Display will show a Zero (all Region-Free),     then press Power to Turn Off.

SOURCE: player won't play any disks only says CANNOT LOAD DISK

change the way you connect the dvd player to your tv

SOURCE: sony dvp ns50p dvd player

If you are using the s-video jack to connect the DVD to the TV, the jack could be loose or the wire could be bad. The s-video cable has 2 signals, the black-and-white (luminance) and the color (chroma). If the chroma signal is not getting through, the picture will be in black and white.

SOURCE: DVP-NS305 DVD Player

Your system is in child lock mode. I had this exact problem this week. You need to put the system into standby mode and then press return, then enter then on/off and it will be unlocked.

SOURCE: unlock region code on Sony CD/DVD Player DVP-NS57P

I don't have a solution, but I know that the one about "press Display, Top Menu, Clear, Power" doesn't work.