Autosave is usually available after a crash. And after any edit changes have been made, VP should prompt to save when it's closed. 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. Never move or delete source files until the project is complete.
Look for the autosaved file in C:\Users\[user name]\AppData\Roaming\NCH Software\VideoPad. Search the PC for other VPJ files.
To help sleuth out what's going on with your VPJ, let someone here take a look at the project. Go to the (hopefully single) folder that contains all the source files and the VPJ, zip its contents and upload to a free server. Get a shareable (public) link, copy the link and post it here or to me in a Private Message (click the envelope at the top-right of this forum). If using Google Drive, be sure to make it "anyone with link can view" and not "restricted."