What is a shape with 1 flat surface and 1 curved surface And a flat face is circular. And a curved surface makes a sharp point. And that does not have any sides and that looks like a party hat?

The shape you are describing is a cone. A cone has one flat circular base and one curved surface that tapers to a sharp point at the top. It does not have any sides, which aligns with your description, and it resembles a party hat in appearance.