I think that you need to get it fixed. If that's not possible, then you might need to buy a new Wii...
Because the files are corrupted.. I don't know if it's something you can fix on your own.
You should contact Nintendo! Or go to their website.
I wasn't much help, sorry ^^'
But I was just assuming it is like when a computer's database or whatever messes up. I might be wrong. Probably =P
I hope you can figure it out, though.
EDIT: I was searching the internet to find an answer to your problem.
It's happened to a lot of people. Sometimes it starts working again, and sometimes the files stay corrupted.
Most of the people whose systems didn't work again contacted Nintendo and they either repaired their Wii, or recieved a new one. But I don't know if they were able to do that because their Wii's were registered, or because Nintendo does it for free...? I don't know about that part.