Narration files are stored on the PC in the MUSIC folder, unless you have changed the path under OPTIONS | DISK tab.
Ran a test with Stacks, added narration, then Saved Project Files AS. That created a VPJ control file (not playable). Closed Videopad. When the VPJ was double-clicked the project loaded back into VP exactly as it had been when saved, narration intact.
Save Project File AS routinely, giving it a unique # or name, so as not to overwrite prior saves. Using Save Project Files (no AS) will overwrite.
What version of Videopad is being used? Test the latest. For licensed users upgrades are free for up to six months from purchase date. After that, VP will continue to fully function but a fee will be required in order to register the newest. Retain your old install file and registration info.