Many of the mesh tools involve selecting or manipulating nodes. Ensure that the nodes in the part are visible and selectable by activating the required layers in the Layers pane.
Use the Orient Elements command: 
() to correct mesh elements that are improperly oriented according to the Orientation display: 
(). This command is not relevant to 3D meshes.
Note: Flip orientation will orient each element opposite to the element's original direction. Align orientation will orient all elements in the same direction as the reference element.