Changing a Sprite-Object's sprite on runtime

Hey there,

I want to change a SpriteRenderer's sprite during runtime. Is there a find function, that returns a sprite, when I give it the name of the sprite?

Code (csharp):

1. Sprite my_sprite = Sprite.Find("my_sprite_0"); // <- something like that

EDIT:
To clarify: I don't want to find the SpriteRenderer (or the SpriteRenderer.sprite), I need the reference for the sprite itself, the .png by name (string).

Thanks,
Sima