Can't use more than 1 SD card?

[AVahne]

So I recently decided to use a 64 GB card in my second slot and decided to format it to ext4 instead of NTFS which I'm using on my 128 GB card. I used the terminal since I forgot that I had GParted installed....and now my 64 GB card is corrupt and I can't reformat it from RAW. Not only that, but now my Pandora is unable to read two SD cards at the same time.
Does anyone know a fix for at least the card slot problem?
[doublepost=1475538518,1475537986][/doublepost]Ugh, nvm, sorry for taking up forum space. Turns out that I just have more corrupted cards than I thought.
My Pandora is fine, I just need to figure out if there's any possibility of saving my SD cards (I don't want to go and buy even more cards).

 

[Yoyobuae]

Check the output of command:

dmesg

Right after inserting corrupted SD card. May show some errors.

It could be that partition table was corrupted while trying to format. Recreating the partition table could help solve that. Does it at least show up in GParted?

 

[levi]

I broke one of my high-ish grade 64GB sandisk cards when I forgot that the integrated reader in one of my machines was broken, and tried to format it using that. Now it doesn't even show up as a card in anything I try it in, perhaps the controller chip on it has been fried somehow, I don't really know, but I've had no success in ever being able to debug it in any way.

But hopefully AVahne's cards aren't as broken as that one card of mine.