Cards (memory cards) tend to fail in one of a couple of expected ways. And in most of those failures there are photos/data available behind a bad photo database/file system or a weak memory controller. But how quickly and carefully you handle things in the first few minutes determines whether or not those photos remain recoverable.
Every card reading device says they will “fix” your corrupted card. Fixing means formatting. One click of that format button changes your file recovery to a carving operation, and occasionally to a recovery operation with no results.
Memory cards operate using either FAT32 or exFAT. Both of these systems update the file allocation tables continuously throughout shooting. If you remove a memory card in the middle of writing data, allow the battery to drain during a burst of shots or pull it out before safely removing it, the file allocation table will become mixed up. In response to this inconsistency, the device will report that the memory card has been corrupted, needs to be formatted, or is unreadable; however, all photographs remain where they were originally written.
That is the best case, and most commonly how recovery occurs. Recovery typically involves repairing the directory structure, or extracting the images based on signature if the directory structure cannot be repaired. This method works since both JPG and RAW image formats have unique headers.
Card failure is also physical. Controller failure causes the card to be undetectable, or read much less than its true storage size. Wear is also present in heavy video use cards (those cards that repeatedly write the same blocks).
The second form of physical failure worthy of mention is counterfeiting. A card labelled 512 GB but made from 32 GB of flash memory with fake firmware will appear to work just fine until catastrophic corruption occurs after data has filled the actual flash. If a card was extremely inexpensive and crashed while there were large amounts of data stored on it, most likely this is an example of a counterfeit and recovery would depend upon what actually ended up being written to real flash.
To begin with, remove the card from your camera and attempt to read it using a separate reader (laptop slots can be problematic; a quality USB reader is cheap). Second, use a different computer. If you are able to mount the card in some manner, immediately back up as much of your data as possible prior to performing any repairs, even though the file structure may appear disordered.
As far as what not to do: avoid running chkdsk (chkdsk attempts to resolve issues by writing over the card and deleting entries that cannot be reconciled); do not allow your camera to “fix” the problem; and never continue taking pictures on this card again since each picture taken will be added to the space currently occupied by the other photos.
Memory cards are from £250 +VAT after a free 48-hour diagnostic and written quote, and in most cases you only pay if we recover your data. Send just the memory card (in a rigid case) as opposed to inside the camera. If possible please provide an approximate number of photos that may be missing and approximately when the photos were taken, as this will help confirm the right photos have been recovered and not simply a large number of photos.
Generally, yes. Card corruption usually refers to damage to either the FAT (File Allocation Table) or exFAT index; therefore, in many cases the actual photographs will remain intact. The photos may be recoverable through an index rebuild process or through carving using a specific image file signature such as JPEG & RAW files as they contain distinct file header signatures.
No, this is the single action most likely to result in your loss of photos. Formatting will rewrite the index recovery will utilise. When prompted by Windows, macOS, and especially by the camera which will offer it when powered on with the memory card inserted, decline the formatting request.
Generally, due to an inconsistency within the file allocation structures remaining: the card was pulled during writing; the battery drained while performing a burst write; or it was ejected without properly unmounting. In general, the images themselves are usually unaffected.
First try a new reader, since built-in laptop slots fail relatively frequently, then attempt another computer. If it remains undetectable, there is a good chance that the controller has failed; however, this is typically a hardware-based problem and is frequently recoverable via a physical recovery method versus being software based.
Prices start at £250 + VAT based on a written quotation provided after our complimentary 48-hour diagnostic. In most cases you only pay if we recover your data. Please send the memory card by itself rather than in conjunction with your camera.