Well… accidents happen as we humans make mistakes. All card manufacturers (SanDisk, Kingston, Lexar, etc.) have also recommended the tip in their user manuals.

That means you are to have either backed up or transferred all useful files to another device. That said, there is no “unformat” option available on a camera or computer, as far as I am aware. However, most photographers do suggest that we format in camera in order to avoid any unexpected compatibility issues. It’s pretty much the same thing whether you format it via your camera or by using a computer. Simply put, a formating operation prepares your card back to the default setting – it marks it as blank (learn more from this Wikipedia page). What does it mean after formatting your memory card? If you can, remove it from your digital camera and put it back into a plastic case (or another safe place). Studies show that the primary reason why data recovery fails is that the user continues to use the storage media with massive data writing activities (such as saving new files), causing the data contained in those files marked as deleted to be overwritten, and thus they become totally unrecoverable.

Note: it’s important that you do not take any additional photos using the same camera card (be it an SD, CF or xD). Stop using the card immediately! That is absolutely the first step you should take. I accidentally formatted my camera SD card, now what? How to Unformat an SD Card and Recover Your Files.Can I still recover photos from a formatted card?.I accidentally formatted my camera SD card, now what?.

How to format sd card for camera