You will have to remove the 12 screws holding the tailgate access panel on the inside of the tailgate and remove the access panel. There you should find the 2 bolts that fell out of the tailgate handle (tailgate control assembly). In your picture, it appears that 2 threaded inserts came out of the handle with the mounting bolts. If they can't be reattached to the handle, you might have to purchase a new handle assembly (tailgate control assembly, as Ford calls it).