There is no such product as “Sony Vegas Pro 16”. I’m guessing you have VEGAS Pro 16 by Magix. Sony sold it over 5 years ago and the last Sony version was 13. The last version 13 was by Magix and 14 to day are by Magix.
What if you move all of the media to a different folder and then “ignore missing files” when opening. Now go back and add them back in one by one. Will it open then?