I can relate as I've been there as have many of our colleagues. That sucks. What can work is a deep search of your hard drives by searching on the Premiere Pro project file extension, which is ".prproj." Just doing a search on that term can often uncover a backup file you can use. In the future, create your own backup folder with a once-a-day "Save a Copy" to a folder in the cloud somewhere; a great safeguard.