SD and memory card recovery.
Don't click format.

The camera or the computer insists the card must be formatted before it can be used. The card worked yesterday.

That message means the file system is damaged — the index that says where each photo lives. It does not mean the card is empty. Your images are almost always still physically present, waiting for something to point at them again.

Formatting writes a fresh, empty file system over the damaged one. It does not repair anything, and it replaces the exact structures a recovery would have used to rebuild the folder tree.

This is the single most common way a recoverable shoot gets lost, and it happens in the first thirty seconds, before anyone has called a professional.

You deleted the wrong folder, or formatted the card thinking you had already offloaded it.

Deletion removes the pointer, not the file. A format resets the index without wiping the content. In both cases the images are recoverable — right up until something writes over them.

Which means the whole game is: take the card out of the camera and stop using it. Not one more frame, not a test shot. Every new photo written to that card is a photo that might land exactly where your old ones were.

Flash media does not have the TRIM problem that makes SSD deletion so unforgiving, so cards are considerably more recoverable than solid state drives in this situation.

No capacity, no name, nothing — in the camera, the computer, or both.

Before concluding anything about the card, eliminate the two cheapest suspects. Card readers fail constantly, and USB-C readers running hot fail faster. Try a different reader and a different port directly on the machine rather than through a hub or dock. And if the card reads in the camera but not the computer, that is a reader problem, not a card problem — copy the files off using the camera as the reader.

If it fails everywhere, the likely cause is controller failure. Every card has a controller that translates addresses and manages wear levelling, and when it dies the card is completely invisible. The NAND chips still hold your images, but reaching them means bypassing the controller entirely, which on modern cards is difficult, expensive, and often not possible.

A file that is gigabytes in size but plays as 0:00, or that no player will open. Common on GoPros, drones, and any camera whose battery died mid-recording.

An MP4 has an index called the moov atom, recording where every frame sits. Most cameras write that index when recording stops. If the battery dies or the card is pulled mid-record, the camera never writes it — so you have every second of footage and no table of contents.

These are repairable. Because the camera writes identical headers every time, the missing index can be rebuilt using a working clip from the same camera at the same resolution and frame rate as a reference.

Cracked CFexpress housings, snapped SD write-protect tabs, cards through the wash, cards bent in a pocket.

Flash tolerates water far better than hard drives do — there are no platters to contaminate and no heads to crash. If the controller and NAND survived, a wet card often recovers fine once it is properly dried. Do not power it on wet.

Physical breakage is more variable. A snapped plastic tab is trivial. A card cracked across the controller or the NAND package is usually not recoverable.

CompactFlash has one failure worth calling out separately: the pins live in the camera, not the card. An angled insertion bends them, and the symptom is that every card you try afterward misbehaves.