What operating system, Mac or Windows?
You should be able to still find the file to recover it when you select Recover from the file menu. The one exception is if the operating system no longer recognizes the file as being a FileMaker file which might have happened when your computer shut down unexpectedly.
Can you confirm that when you tried to use recover, you were able to navigate to the directory (or the desktop) where the file was located, but it wasn't listed in the dialog box? And that this was the location of the actual file, not an alias or shortcut to that file?
If you aren't sure if you are looking at the actual file or a shortcut to it, you may want to check properties (windows) or get Info (Mac) to see and if it is a short cut/alias, this is also a way to find out where the actual file is located.
Ultimately, you may not be able to recover your file. You may have to use the most recent back up copy you have of your file.