That message is easy to misread. The camera or computer isn't saying your photos have been destroyed — it's saying the card's index (its file system) has become unreadable, so the device no longer knows where anything lives. Beneath that broken index, the photos themselves almost always sit untouched in the flash memory. Which is what makes the prompt so treacherous: the button it offers is the one that starts erasing the map a recovery is rebuilt from.
A format doesn't repair an index — it replaces it with an empty one. Let a corrupted card be quick-formatted and the structures carrying your photos' names, folder layout and dates are written over in seconds. When the pictures matter, decline every formatting offer, every time.
Move the card to another reader before blaming it — readers die more often than cards do, and the slot built into a laptop is the least reliable reader of all; a decent standalone USB reader makes a fairer test. Try a second computer too. And on full-size SD cards, inspect the small lock slider on the edge: knocked into the locked position, it produces genuinely odd symptoms, including a refusal to write or format.
If the card mounts but shots seem to be missing, retire it that instant — no test photos, no letting a camera or phone write a single thing — because anything new lands on top of exactly the data you want back. And if the card shows up nowhere, or announces an absurd capacity (the 64GB card claiming to be 30MB is the textbook failed controller), put the software away: only chip-level work reads a card in that state.
Plenty of people meet this from the other direction: the card was misbehaving, they decided to wipe it and start again, and the format itself refused to complete. That refusal usually means the lock slider is engaged, the controller has retreated into read-only mode as it fails, or the card is dying electrically. The read-only case is quietly good news — a controller that locks itself often preserves the entire contents in readable form.
What matters is not to escalate: repeated formats, chkdsk loops and repair utilities all pile operations onto a controller already struggling to manage any. A card in this state that ever held something precious should go for recovery, not another round of fixes.
In the lab, a corrupted card is read once, sector by sector, into an image file — all rebuilding happens on that copy, and your photos and video are reconstructed from it. Cards that are dead, misreporting their size or physically broken (snapped microSDs included) have the memory chip read directly and its contents reassembled. Both routes open with a free diagnostic, so you'll know what's recoverable, and the fixed price, before deciding anything.
Posting is trivial: tape the card inside a folded sheet of card, envelope it, send it tracked. The memory card recovery page has the detail, or go straight to the free online diagnostic.
Remember: a card demanding to be formatted has lost its index, not your photos. They're normally still in the memory beneath — right up until a format or new shots write over them.
Free diagnostic on arrival, one fixed quote, no fix no fee on logical faults — start online or pick up the freephone.