I was already transferring it to the Wii U. At 12% there was an error message regarding Prince of Persia save data. I deleted them as an given Option besides a restart. But after that the SD Card wasn't readable anymore.
Well, my Virtual Console data and all things regarding the Wii Shop are there. Some save Data (The Last Story and Xenoblade (thank God!)
Well at last, I'm lucky it seems. Put the SD Card back in my Wii and there they are: Save Data from Galaxy 1 and 2, Prime 3 and Other M Excite Truck!, Skyward Sword and Fire Emblem. But many others are lost like Twilight Princess, Super Paper Mario...