OH MY GHOD!!! Do
NOT follow trunglinh06's instructions. The μSD card has multiple partitions, only one of which is accessible by Windows. Formatting the card will erase all the partitions including the system and recovery partition. At that point you will need to get an image of a working Aura Ed. 2 μSD card and use the appropriate tools to write the image to it.
See the
Memory Upgrade Mod Guide (With Pictures) thread for more on the process and tools needed.
And yes, quite a few people have requested an image file after formatting their μSD card using Windows.
You can request an image by posting in the
Kobo Aura Edition 2 SD card image thread.