Normally, if the thing you want to know falls into one of the "bad" categories, there is no way to reformulate it. If you want to know all uses for garlic, for example, there is no formulation which will both provide the answers you want and will be accepted here.
But in this case, there is a loophole you can use. We normally don't accept "list" questions, for their tendency to have way too many answers. For "what to do with X", you are encouraged to search for recipes with X on the internet search engine of your choice. But we have the culinary-uses tag for issues like yours. If you have some food item which would be thrown away (like potato peels, or, in your case, overhardened bread crust), because 1) the list is fairly short, 2) you are unlikely to find recipes for hard bread crust, and 3) most information from the answers will probably be new and worthwhile for the community. So, you can go ahead and ask it.
To help you with language, you can use a formulation like
Are there uses for too hard bread crust?
And then explain in the body that you baked a bread whose crust is too hard to eat. By the way, this should not happen in principle, it is completely possible to make bread at home which has pleasantly crispy crust. But seeing that you already have a loaf with bad crust, and may happen to bake more of them before you get your baking process under control, you can ask what to do with the crust in the meantime.