If you have interrupted its deliberations before it finished you may need to delete directories:
c:\users\username\AppData\Fritzing\roaming\Fritzing (which is a hidden directory so you need to enable hidden directories in explorer) and
c:\Users\username\My Documents\Fritzing (where username is your windows id)
as the database can get corrupted if you interrupt the parts update and these directories don't get touched even on a rinstall of the program. If you just delete them Fritzing will recreate them and fill them appropriately.