Love and Care of Your Camera’s Memory Cards.
Use good cards
Use camera with built-in backup card
Promptly copy photos to a computer's hard drive and to an external card or drive, for 2 additional backup copies.
Use a USB cable to download photos to a computer
Format a card as a last resort, it destroys the contents
Recovery programs can be risky and “free” programs often contain parasite software.
Store spare cards in a good card holder.
A knowledgeable friend who uses excellent photo equipment just lost all her underwater photos, taken while diving in Indonesia, and stored on a single SD card. That prompted me to review the prudent handling of SD cards, and to recall that the witches in Macbeth, I am told by reliable witnesses, were heard to chant:
“Double, double toil and trouble,
Fire burn and underwater camera bubble.”
Memory Card Love and Care:
When I asked about SD cards, the first thing knowledgeable friendstold me was to buy an excellent make of card such as Lexar or SanDisk from a reliable supplier.
After a photo shoot, they use a card reader to copy the photos to the computer's hard drive, but they do not manipulate the photos in any other way; from the computer they click the Windows Eject option before disconnecting the card reader or removing the SD card.
Another top photographer goes even further, and does not remove the SD cards from the camera. Instead with a USB cable he connects the camera to the computer, then he transfers the photos to the hard drive for manipulation; he only copies but does not delete, rename or otherwise manipulate the SD card files. When the SD card approaches full, he formats it with the camera's utility. Before connecting a camera, cable or card reader to a computer, he first makes sure the equipment is turned off and suitably grounded, to avoid sparks or static electricity.
Another safeguard is to use a camera with two built-in cards, SD + SD or SD + CF, such as the Nikon D7000 and D800, and the Canon EOS 5 series, and later models. The Menu is set to record photos to both cards. Card A of my Nikon D800 is an SD card, with a second SD card in a CF to SD card adapter as Card B, so both record my photos as they are taken. After, I connect the camera to a laptop via a USB cable and copy the day's photos to the hard drive, from it I back up to a USB thumb (flash) drive. Then I edit the hard drive photos.
In tropical hot humid weather, the use of an USB cable to download the photos and charge the battery has the added advantage of not having to open one or two of the camera's large hatches, preventing hot humid air from entering the camera and possibly fogging the lens.
Recovery of Lost Photos:
Do not format the SD card as this will destroy all information. Use a different card reader to test the card. If two different card readers do not read the SD card, try to recover the photos with a free file recovery program, such as Disk Digger, EaseUS Free Data Recovery or ZAR (Zero Assumption Recovery).
Some free recovery programs limit the number of files or amount of data they recover, so look for data-size limitations before trying the recovery. When using a "free" recovery program offered on the web beware of pirate, hitchhiker software, do not use the 'Recommended' installation option, it often installs parasite programs instead of what you want, which is why the program is "free". If one searches the web carefully, it is at times possible to find a genuine free program that does what it should; user beware.
Choose 'Manual' recovery and carefully read each screen, opting out of search bars and other options. Now select the SD card, allow the program to analyze it, after which it will repair and provide a list of recovered photos. Have the program write the recovered photos on a separate folder on the hard disk, not on the SD card.
How to Fix the SD Card:
Rather than fix it some photographers will simply throw the problem SD card away and use a new one. If you choose to fix it, put the Write-Protect tab in the Write (unlocked) position, then use Windows Explorer or similar to analyze and re-format the SD card. Or better, place the SD card in the camera and reformat it with the camera's program, take one or two test photos, after which you can enjoy shooting away. But, check your photos as you go along.
My personal problems have been mainly with micro-SD cards and with their adapter micro to SD cards, such that I only use micro-SD when absolutely necessary, but I grant that this is a superstition on my part.
Card Formatting, Handling and Storage:
Wikipedia has a discussion written in almost-understandable jargon.
When handling an SD card, it is a good idea to touch a grounded surface to insure one's hands are static free. The SD card should be handled by its square end, not the end with metal contacts, to prevent micro sparks. A good idea is to store and carry the cards in an SD card case.
Links to recovery sources:
6) https://en.wikipedia.org/wiki/Secure_Digital (useful to begin to understand the gobble de gook.)
7) Recover formatted card content: http://wetpixel.com/...showtopic=51821