go to supercheap auto, and grab a bendy magnet. Its a long flexible device with a powerful magnet on the end.
Poke that down there and it will grab it.
Just recently when replacing my airfilter, I dropped a nut down the afm into the mouth of the turbo. Instead of pulling the whole intake off, and possibly the turbo, I blindly shoved my bendy magnet down there, and out came the nut.