Is the problem that the Premiere project file (*.prproj) is missing? If so, how are you searching for it? Through the operating system's file browser? By clicking Open in Premiere's Welcome dialog? Have you used the OS's search function to scan your whole computer?
Or is the project file right where it should be but when you open the it you can't find your sequences and assets? If this is the issue, then please start by going to the Window menu, then the Workspace submenu, then click Reset Current Workspace. If you still have a problem, please post a screenshot of the entire Premiere Pro window.