I updated and lost all my projects 
the fritzing map on windows documents is empty
Is there a way to get them back?
Which operating system and what did you update (presumably the fritzing app, if so which versions from and to)? By projects do you mean your custom parts in the mine parts bin or something else? In general Fritzing preserves the user directories during an upgrade and the mine parts bin should be there and be recoverable (they are in different places depending on operating system though.) If you mean the recent sketches window on the welcome page, yes as I recall that gets cleared in an upgrade, but the projects are still present in the file system and will populate the recent sketches window when you open one via file->open then navigate to the .fzz file for the sketch and click on it.
Peter