Check whether...
1. The clip is muted or its volume is turned down. Click the little speaker icon at the bottom of the clip itself.
2. The track is muted. Verify that there is no red X in the speaker icon that's to the left of the audio track.
3. The PC's audio for VP is turned down. In Windows, right-click the speaker icon in the notification area - right-hand side of the taskbar - and Open Volume Mixer. Use the horizontal scrollbar to see the Videopad slider.
If none of these measures succeeds, please upload your clip. Let's check it out. Here's how... http://nch.invisionzone.com/topic/23659-tips-for-getting-help-on-this-forum/
No need to upload the project - just the clip. Be sure to share it.