Did your 4x4 fall apart, mine did! Here's how to put it back together.
Note: the 4 different types of pieces are the centers, Right edges, Left edges, and corners.
Step 1: White Centers
This step is a bit tricky, because the centers fall out easily. Put the corner of the hook in the center, see pictures.
Step 2: White Edges and Corners
Now put the pieces back in as shown.
Step 3: Second Layer
Follow the pictures to put together the second layer.
Step 4: Third Layer
Follow the pictures. Put the other edges in after you put the centers in.
Step 5: Fourth Layer
Follow the pictures to finish the cube! When you put these edges in, put a portion all the way in, and snap the other side in.