There could be a number of reasons for why a game won't work.
1. Is the game disc dirty or scratched?
2. Is the Wii's laser lens dirty? (Do other games play okay?)
3. Does your Wii have the latest system update?
4. Have you improperly "Homebrewed" your Wii?
5. Skyward Sword requires Wii Motion Plus. Do you have that or a Wiimote Plus?
If you have no luck getting the game to play and other games seem to play okay, report the disc and request a new one: