Sadly, a few years ago I lost all of my family videos when switching from Windows to Apple and back to Windows. I did recently find a number of Vegas sfk files and some veg.bak files. Can I reconstruct my family videos from these .sfk or .bak files?
SFK files are only graphic files of the audio. You might have some success with the bak files. These are normally backups created automatically while editing.
Why should a few kb/mb's bak files be of any help?
If you still have the source material you can open up the project again from the bak files after renaming them. But if you don't have the source files then they are of no help.