I'm not sure what is the easiest way. In any case I would rename your desktop file to something like MyFileOld and that should rename the file, the media folder associated with it and change the sync controls to reflect it.
Then I would sneakernet the full backup from the laptop over to the desktop and try restoring it.
One problem you might run into is with the Media on the laptop. If you have just linked the media to where you normally keep it instead of copying it to the FTM Media folder I would go ahead and change all of the Media from link to copy before trying any of this.
And unlinking can't be undone. If your tree on Ancestry and the laptop are in sync it may be easiest of all just to unlink the tree from the laptop and then download it as a new file on the desktop with a new set of links. Unfortunately you will lose a lot of the notes that are in FTM doing it this way.
Just my 2c worth. It's always messy when this stuff happens.