There are tools / software you can use to recover items. ('File Recover' and 'Recuva' off the top of my head)
When you first delete (for an example a folder) and it goes to the recycle bin, it is basically still in the same place, but the file is renamed, and the path (how you get to it) is hidden.
When you empty the recycle bin, you basically tell the computer, the space that the file or folder was used for, is no longer needed (and can be overwritten). Until it is overwritten, the file still exists and you can get it back (again software).
So you can recover it - depends wether or not the info has been overwritten. You could get some things back and not others etc.
Hope this helps