Instructions
Turn the Nintendo Wii off. Unplug it from the wall for a minute. Reconnect it once that time has passed.
Turn the Nintendo Wii on. Press the "Sync" button located on the front of the Wii. Hold it for approximately 15 seconds. You must now manually re-sync all the controllers you want to use.
Get the first Wii remote. Remove the battery case, and press the red "Sync" button located under the batteries. Immediately press the "Sync" button on the Wii after you do this. The four lights on the front of the controller will blink. When the light furthest to the left (indicating the player 1 controller) stabilizes, that will mean that the controller is synced.
Repeat Step 3 with the second Wii remote controller.