Stories that are x/F or x/f where the girl is trapped some how and spanked.

There was a flash game called "girl in a window." Which involved a young woman who gets caught climbing out of her bathroom window. You get to do a lot to her getting her worked up until she was enjoying some of the humiliating things that's done to her.
A couple years ago, someone made a comic based on the same basis, including neighbors who walk by and talk to her inanely while the guy who is "helping her" decides to help himself, much to her embarrassment.

Not a "story" as you asked, and I'm not sure if any spanking was involved, but a one shot that is freely available to those who seek it out, and not bad as a sexy short story with some bondage elements thrown in.

There was a story somewhere about an automaton where a girl puts herself in place of an "doll" and takes an otk spanking and brushing.. I can's remember where to find it though.

Barretthunter wrote a few like this, I think.

@milf I recently read that story. It's by Mark Hall and it's called Clara and the Automaton.

Another story that might fit this topic is Zero G (part 1 by Flatfish, part 2 by Gloup) which features both a young woman who wants to be spanked by a machine and her friend who gets trapped by mistake and receives the same treatment.

You might try Blasted Off by Gloup. It's a sci-fi version of this theme.

Hi, you might like my story "Titan 5" where a young woman is trapped and spanked by an industrial robot. I also have one of the burglar trapped in a window type "Burglars" and not totally on theme but "The Princess and the Wooden Soldier" may also interest you.

There was a really good one that fit that theme on the old chross.chan forum, if those stories still exist somewhere. It was about a young lady who enjoyed fantasizing about being spanked, and would go down to a private pond and daydream about being spanked.

Another young lady steals her clothes and bike after discovering her, and when she tracks down her bike, she tries to sneak in, but gets trapped in the window and then spanked when discovered.

I've written a story a bit like that. "The Pennington Automatic Discipline Booth" involves a girl "accidentally" getting trapped in an automatic spanking booth.