I've heard that people who work at amusement parks/roller coasters always walk the areas underneath the rides after closing. They know that stuff falls out of peoples pockets and they find all sorts of interesting things. It's a safe bet someone found that stiletto and had a really good day. Sorry for your loss.
As for my story- When I was around 11-12 a friend gave me a little bowie knife with around a 4" carbon steel blade and black plastic handles pinned to it, it might have been an Imperial brand. It was my first fixed-blade and I really liked that little knife. It didn't come with a sheath so I made one out of some bicycle innertube and I carried it on my ankle under my pant leg.
One day I was at the shore, and I was crawling around on the side of a jetty (like a dock made of rocks that extends out into the water with compressed dirt on top for vehicles and people) chasing after the little crabs that occupied the rocks. The knife fell out of the sheath, and clattered down between the rocks. I crawled down to where it went in, near the water line of the ocean, and I could see it down between the rocks. It wasn't too far in, I could have easily reached in and retrieved it, but the tide was coming in, and waves were crashing against the rocks, and the rocks near the water were slippery. I knew that I would be risking my life if I tried to retrieve my knife. So I had to abandon it.
It was the right decision. And I was actually proud of myself for making it. I could very easily have been a story on the news of a kid who fell into the rough surf and drowned. I didn't know how to swim, and the water was very cold.
There's no chance of anyone ever finding that knife. And I sometimes think about it. It must still be there, down between those rocks. Likely it's just a sliver of rust with plastic handles attached to it now, if there's anything left of it at all.
The crabs won that day, and claimed their prize.