@lvartist
Adobe doesn’t create a folder called WIP_PSD on its own. It’s almost certainly a folder you made on your PC. Because of that, Bridge won’t be able to recover it if Windows has moved or removed it — you’ll need to search for it through Windows Explorer instead.
By any chance do you save your WIP on your desktop? They’re more at risk than files stored in regular folders on your hard drive. After a restart, Windows can load a temporary profile, reset the Desktop, or sync it differently, and that can make Desktop files disappear even though everything else on your drive stays intact.