Very little info, I am going to pretend that you are new to godot and you did not read the manual. In the Inspector, in the Sprite property "Texture" you have to assign a texture, you can try the godot icon that comes by default when creating a project. Below, there is a property called "Visible", verify that it is activated. Just below are the modulation colors, if the alpha is at zero, the sprite is not visible. I can not think of anything else, if it is not solved can you provide more info?