When I load a dvd into the player, after a while it says "no disc" and nothing plays.

SOURCE: Cannot play this disc

remove the cover and see if the dvd run, if not you got a motor problem or a motor drive one,if yes then try cleaning the reading eyes(pickup)by blowing dry air (get a can at radio shack)check for goods, if dosent work, take it to a shop for a repair thats all you can do, is a job for a tech....good luck

SOURCE: Samsung 3650 dvd/vcr player loading problem

Sorry, no suggestion other than don't buy Samsung. That's my conclusion after owning the same model. It worked fine for a while, but now won't load any DVD... usually. Sometimes it will play one, but more often it won't. Mine tries to load ("Loading") for a long time, I hear the DVD spinning, then ultimately the screen displays "This disc cannot be played" or something to that effect.

SOURCE: Nexxtech N700-PD DVD Player - Discs will not load

Tracking motor has to be replaced

SOURCE: player won't read a DVD

Sounds like a bad pick up assy (Laser)

SOURCE: Toshiba DVD SD-3980SU2 or SC2 player loads every disc as "bad disc"

Toshiba says:
Information for Owners of Toshiba SD-3980 and SD-K750 DVD Players To ensure the satisfaction of our customers and to maintain the integrity and quality of our products, Toshiba America Consumer Products, L.L.C. is issuing an important product update. This is not a safety issue.
Toshiba is committed to customer service and to continuously improving the quality of its products. It has come to our attention that certain DVD players bearing the model numbers SD-3980 and SD-K750 may at some point in their life stop playing discs due to a component part failure. In such case, the error message "bad" will be shown on the unit's display. Affected units will have "SU2" at the end of the model name (e.g., SD-3980-SU2), which can be found on the back of the unit.
If you own either of these models and experience the issue described above, please contact Toshiba Customer Solutions at 1-800-631-3811 for information on how to obtain a replacement unit.