To protect your work, 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. From the HOME tab, that choice is available by clicking the chevron to the right of the Save Project button on the toolbar.
Then clicking on the latest VPJ file will load the project into Videopad, just as it was when saved.
This is not an export of your work, but a saved project that lets VP reconstruct it - as long as source files have not been moved or deleted.
Search the drive for C:/Users/<username>/AppData/Roaming/NCH Software/VideoPad - autosave.vpj" If available, that file may save the day.