I can't hear sound files I embedded in my presentation.
You must have a sound card and speakers to hear sounds that you add to your presentation. Also, verify that your volume is turned up sufficiently to hear the sounds.
I opened my presentation in PowerPoint 2000, and the animations don't work.
The features and functionality of PowerPoint 2002 aren't always available in previous versions of the software. With animations, PowerPoint either converts animations to effects supported by the software version you used to open the presentation or eliminates the animation effect entirely, depending on the type of PowerPoint 2002 animation effect you applied.