What is the cause of the error on the screen?
public struct YetkiYapisiListesi { public bool STOKGUNCELLE =false ; public bool STOKSIL=false; public bool STOKLISTELE=false; } Non-static struct member cannot have initializer
C# does not allow structs to have initializers, the reason why has been debated before, see here: ( Why can't I initialize my fields in my structs? )
Simply remove the = false part from your field declarations.
Note that Boolean fields are false by default, making your assignment completely unnecessary.
If you absolutely need fields to have initialized to non-default values then you can still define an additional constructor that sets those values, however it cannot be the default (parameterless) constructor. One alternative option then, is to use a static factory method.