I just came across this. I had some files deleted early this morning and then needed to get some of them back - but for a strange reason my Bin was empty.
As it turns out the issue is due to a bug in Windows 7. I have a codemeter usb stick plugged in and the company behind it provides a download link:
which points to
"Assume that you connect a removable hard disk drive to a computer that is running Windows 7 or Windows Server 2008 R2. The removable hard disk drive is read-only and does not contain a Recycle Bin. In this situation, when you open the Recycle Bin on the desktop to restore some files, no deleted files are displayed in the Recycle Bin."
If you cannot install the hotfix - for Codemeter another solution exists by changing the codemeter configuration.