Don't delete or move source files. 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 caret to the right of the Save Project button on the toolbar. That's your protection.
You can test the latest Windows release (v13.21) as a trial, then reinstall 8.42 or upgrade. Projects will be backward compatible. But those made with 13.21 or other recent versions may not load in 8.42.
Only a single release can be on the PC at any one time. If you do not have your 8.42 installer, it and all others are available here. Ignore any virus warnings.
To create a portable project that can be loaded onto any PC that has VP installed, first have the project loaded. Then click the 3-lined Menu at the top-left. Click FILE | SAVE PORTABLE PROJECT AS. All source files and the VPJ control file will be saved to the drive and folder you choose.
It will be dated/numbered, like this...
To load the project, simply double-click the VPJ.