i think running the updater again should fix it by downloading the file and if not then manually downloading the zip and placing the missing file to your sdcard should work
and if i find the sd card i have my NAND backed up on, i can not only restore the NAND if i solder the right part in, but i can also put my NAND on dolphin, then i can play dolphin online, like PMEX Remix or MKWii Riibalanced