My Canon video camera all of the sudden WOULD NOT recognize my SD card. The video camera would not even let me TRY to format it.
The weird thing was that my computer would read it just fine. So, I tried to reformat with the computer.
Still no luck.
Finally I inserted it in my Canon Rebel camera, and low level formatted it. THAT worked.
Keep in mind I have been using this card for weeks. Why this hack worked, I do not know.