You lost me. Why is the track empty? Did you delete the clips from the track? If so, then the track is the way you left it, as it should be.

Or do you mean that the clips themselves are no longer in the same place on your hard drive so the events all come up blank with 'media offline'? If so, go to view and enable 'active take information'. That will show the clip name in each event. Also, in these cases when you open the project Vegas should have stepped through each missing file and assisted you in finding it.