Your computer is not an AMD Sempron. That's the brand of the chip inside.
Your computer is something like one of these:
HP (Hewlett Packard)
Compaq
Dell
Gateway
Lenovo
IBM
Toshiba
eMachine
Sony
and that name should be on the box. Please post back.
I have an HP, and it came with its own DVD-playing software. Other brands may not, but Windows Media Player ought to do the job.
So my next thought is that you made need to check for Windows updates. Click on you My Computer icon or use your Start menu to get to the Control Panel. In the left margin, you will see Windows Update listed. Click on that and follow the directions.
Then try your DVD again.
One more thought: Do you have only the one DVD? It's always possible there's something wrong with the DVD and not the player. If you can, test another DVD in the drive. And realize that most DVDs are silent at the beginning, when they're flashing the FBI anti-piracy warnings and such.