And it sucks. The files I 100 percented Pikmin 2, unlocked everything in Smash Bros Melee, and completed the whole of story mode in Mario Party 4 have all been corrupted. 

Is there anything I can do?

Download Dophin Emulator

They didn't necessarily corrupt. I've blown into the memory card port and it worked fine after. Try that

Oh man that stinks.

I feel like you can redownload them from somewhere. IIRC a youtuber I watched had a corrupted memory card and he just said screw it, bought some kind of peripheral, and downloaded the 100% save files he didn't feel like doing over again. Not sure how exactly he did it though.

If you really care enough just 100% those games all over again! Seriously, tis what I did with Pikmin, Thousand Year Door, among other favorite games after losing memory card after memory card.

Yeah I know it's just a long process. The thing that really made me made was Smash Bros. no way I am gonna try to get everything unlocked on that again (it doesn't even matter though I barely play it anymore).

Exactly! You can just not care lel.

Man that's too cruel. I went through three Gamecubes and 5 memory cards because of my family and it was after I 100% at least to games at a time and I had to do it over again.

At best its enjoyable toturing speedruns

That can happen? That's terrifying.