Cast To HUD from a HUD

Hi, I want when I click JOUER, the game loads the save part and the part is registered in Ui_PAUSE,but is not working

Casting does not work this way. You can cast only between classes which are derived one from another.
In your case, you should get a reference to another UI widget to be able to call it’s methods.
Not sure how exactly you’re spawning your widgets so can’t say how exactly it can be made.

For instance, if they are spawned one from another or from a single common source – then just make a variable of the required type and pass the reference into it.

so what do i have to do so that when i press play in my HUD Menu, my button sends information to do function f_charger(load*) ?

There are different ways possible, it depends on how do you spawn your widgets. Here is a possible example: