The DVD is stuck inside the machine.

Without knowing what model you have, I can only offer general advice, so here you go.

First off, look for any small holes in the front of the DVD drive; it's common for those to be manual eject mechanisms that are activated by sticking a straightened paper clip into the hole. It will push the DVD tray out slightly, at which point you can grab it with your fingers and gently pull it completely open.

Apparently some Samsung players have an eject hole on the bottom of the chassis under the DVD player. It's actually more of a slot that you stick a small screwdriver in and move it within the slot.

Move it in the direction shown.

Those are going to be the most likely ways to get it open, but the Free Video Workshop's page has several more suggestions to try.

Open a DVD Player Tray without Power Supply to Remove a Stuck Disc

Good luck; let us know what ends up working for you!