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// case file · Memory card · SanDisk SD · formatted

A single click formatted the wrong card.

Two decades of teaching material, lost to one stray click in a dialog box — yet physically every byte still present. A quick format erases none of your data. What it erases is the index that locates it.

← All case files · £250 + VAT, flat

Device

SanDisk SD memory card

Failure

Quick-formatted in error

Key finding

Data region untouched

Outcome

File system rebuilt from the raw image

// the brief

What arrived, and what was at stake.

The owner had formatted the wrong thing entirely — the SD card in place of the drive they were aiming at — and twenty years of lesson files, worksheets and presentations dropped out of sight. A free recovery tool downloaded off the web turned up nothing, which left them sure the files were lost.

Nothing was lost. Not one file had so much as shifted.

// on the bench

What the diagnosis found.

A quick format clears the catalogue. The books stay exactly where they were.

What really goes on is this. A quick format lays down a clean, empty allocation table — the register of which blocks hold which file. The blocks themselves it leaves completely alone; every one still carries precisely what it did a moment before. The card looks empty for one reason only: its register is empty. The files are all exactly where they were.

So recovering them comes down to discarding that register and instead reading the card block by block — hunting the byte-signatures that flag where a JPEG, a PDF or a Word file starts, and piecing each one back together from its own contents rather than any index.

Two errors will wreck that, and they’re exactly the two things people do first. The first is adding anything to the card: take one more photo or save one more file and it can land straight on the blocks you were counting on getting back — which is the whole reason the very first move is to stop using it. The second is picking a full format rather than a quick one, since a full format sets out to write over every sector, and that genuinely wipes what was there.

And one thing worth keeping in mind, because it runs directly against how an SSD works: an SD card sitting in a camera has no TRIM. No background process is quietly scrubbing the free space. Delete a file from an SSD and it’s typically zeroed inside seconds and truly unrecoverable; leave the same file on an SD card and it stays put, untouched, until something writes over it. Same slip, opposite result, entirely down to the medium.

01

Writing anything new to the card

another frame or another saved file can land on the blocks you want back — which is why step one is always stop using it.

02

Choosing a full format over a quick one

a full format writes deliberately across every sector, which really does destroy the data.

// the recovery

How it was done.

We took a full image of the card behind a write-blocker, so nothing could reach it while we worked, then set the empty index aside completely and carved the files straight out of the raw image by their signatures — JPEGs, documents and presentations — before rebuilding them into the folders they came from. The card itself was never anything but read.

// outcome

What came back.

From the raw image the file system was pieced back together, and the entire teaching archive returned with its folders just as they had been.

Recoveries from a formatted card usually turn out well, for one straightforward reason: the owner stopped in time. What settles the outcome is hardly ever the format itself — it’s how much got written to the card afterwards. Put it away the instant you notice and you’re close to a full recovery; keep shooting through the weekend and the frames you’re after already lie beneath a weekend of new ones.

// the transferable bit

What to take from this.

The second it hits you: pull the card. Not after one more shot. Not once you’ve saved off whatever still appears. Out, then and there.

And keep recovery software off the card itself — most of it writes its own scratch files onto whatever it’s scanning, and on a card this small those can come down right where your data lives. If it’s important, image the card first, or have someone do it behind a write-blocker.

What rescued this one was simple enough: the owner downed tools and brought it straight to us.

// read next

Related.

// your turn

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Bring the drive into our Guildford Business Park reception, or send it by post — finding out what went wrong costs nothing. You’ll get a written figure from our fixed bands before any work starts.