We will attempt to walk you through re-assembling your pencil sharpener
Place piece #2 into piece #1. Make sure to orient piece 4 so that the cone points downward.
Place piece #3 on top of the center cylinder in piece #1. There are two tiny plastic protrusions opposite each other on piece #3- these lock into place on the top of the cylinder.
Place piece #4 on top of piece #1. This will screw on for a quarter turn, clockwise.
If you are experiencing any further difficulty please let us know in detail, with pictures, the issues you are experiencing.