Window crank and handle
You have an old style operator which takes the "male" hex handle that Roto made. What happens with this type of operator is that the black plastic collar wears out and fails to secure the handle. That means you'll need a new operator, not just a handle.
Take a look at the 39-393 awning operator to see if this matches up to yours. I can't tell based on just the base, so if you aren't sure we'll have to see a photo of your operator out of the window. You will also need either the 39-114L handle or the 39-205 folding type.
One thing I've done in the past is pad the "male" hex part on the handle with tape. This allows it to stick better in the "female" part of the operator and may allow you to crank the window open. It's not guaranteed, of course, but I've had a modest amount of success for the effort.
Aside from that, you'll have to play it by ear. It really depends on how significant the damage is.
Thank you for your suggestion with the tape.
Thank you! This is a huge help. I think you could use our 39-326 as a substitute. Look it over and let me know what you think.