What would happen if my SD Card... Er... Vanished?

I have no frickin' clue what happened, but my SD card with all of my Homebrew apps and everything is missing.

I'm going to be looking everywhere but if I don't find it will I have to re-do Smash Stacks or something in order to get HBC back?

Is HBC still on your Wii? If it is, all you need to do is replace the SD card and put the apps back on there.

Removing the SD card will not remove HBC. You just need to put the apps on your new SD card if you can't find it.