How do you recover your deleted files from a Wii?

Ok, I deleted my Wii's mario game file, but you can't retrive it. However, if you find someone who has a higher level/close to you, you can switch files, or copy. In Super Mario Galaxy 2, I used my deleted file for my brother's, and I used my brother's and put my face on it. So now my brother has the one with 0 stars but you can do that, if that helps.