Please check out this thread. And search the PC for VPJ files, which are created each time a project is saved.
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. That should protect you.
Let us know. There may be other suggestions.