Do you have the part that sits inside the crank?

We can help, but your project is a little more involved than it seems at first glance. The part you're looking to replace is called the "worm gear;" that's the corkscrew looking component attached to the bottom of your handle.

The bad news is that the worm gear is machined-pressed into the operator at the factory and it's not possible to repair or replace it. Your operator has been irreparably damaged and will need to be replaced entirely. Your handle, coincidentally, is probably in perfect condition and can be safely reused.

The good news is that we carry a wide variety of different operators and odds are good that we have an exact match for what you need. You can start your search here. If you're having trouble finding what you need, you can submit a few photos of the operator here for me to review. Please make sure that the operator in question is fully removed from the window, though, or at least as unobscured as you can possibly manage. I have to see as close to the whole unit as possible. Figure that the more of it that's obscured, the less likely I'll be able to find a replacement.

Feel free to reach out if you had any questions about this process, I'm always happy to help.