My Samsung dvd player won't play any movies anymore. It says " This disc cannot be played. Please check disc.

Clean the laser.

Don't take that literally and go inside and wipe the laser lens with lens cleaning paper. You can buy a lens cleaning disk for a few bucks. You should have one anyway since they work on settop players, PC DVD drives as well as Blue-ray drives. It's just a disk with a small brush on it that spins quickly past the lens without touching it, but removing debris with wind and static removal. If that doesn't do the trick try checking the connections of the drive and see if they're secure. Finally you can go into your Device Manager, find the drive and uninstall the drivers then reboot the PC so Windows can reinstall the drivers. That works if the driver somehow became corrupted. Have you added any DVD type software recently like a player or burner? Sometimes they can screw things up and an uninstall and System Restore to a point before the software was added can help. Avoid Roxio software, it has a tendency to screw things up so bad even a system restore won't fix it (at least the last time I tried it, I gave it a second chance after a first bad experience and ended up reinstalling my OS again it was so screwed up).