Cards fail silently and completely, because what usually gives up is the controller rather than the memory holding your pictures. This page covers the six ways a card announces itself, why the format prompt should always be refused, what makes a monolithic microSD a harder job than a full-size card, and what the flat £250 + VAT flash band buys.
Every memory card is £250 + VAT — SD, microSD, SDHC, SDXC, CompactFlash, XQD and the rest, at any capacity. The diagnostic is free, the figure is fixed in writing before work begins, and logical card jobs carry no fix, no fee.
Cards give almost no warning, so the symptom you are looking at is usually the first sign of anything. These are the six that turn up most often, and two of them are far better news than they look.
A body that has happily used the card all day suddenly refuses it. Nine times in ten the pictures are still there and only the small area holding the file allocation has been damaged, often by the card being pulled while the buffer was still writing. Take it out and stop using it; a second shot at the same card is what turns a good job into a poor one.
The card mounts as a drive letter with no size, and a dialogue appears asking whether you would like to format it before use. Decline. That prompt appears when the file system header is unreadable, which is a different thing entirely from the data being gone, and accepting it writes a fresh empty structure over the map of where everything lives.
No drive letter, no light on the reader, no sound from the machine. This is usually the card controller rather than the memory. Before assuming the worst, try a second reader and a second machine, because a tired card slot in a laptop accounts for a surprising share of dead cards that turn out to be perfectly healthy.
Thumbnails that render as grey boxes, video files that report zero length, JPEGs that open half an image and then break into coloured noise. Partly written frames like this come from an interrupted write or a failing region of memory, and quite a lot of them can be repaired frame by frame from the raw data rather than through the file system.
Trodden on in a hotel room, run through a wash cycle, snapped in the slot. A full-size SD card is mostly plastic around a small board, so physical damage is not the automatic end of it. Do not dry a wet card with heat and do not try to power it up while it is damp.
Intermittent behaviour, or a card that turns read-only without being asked to. That is normally a controller retiring blocks faster than it can manage, and it is the one symptom that gets rapidly worse with use. Copy off whatever still reads immediately, then stop, because the working windows get shorter every time.
Every secure digital card holds two separate things: the flash memory that stores your pictures, and a controller chip that decides where in that memory each block actually sits. The controller exists because flash wears out. Cells tolerate a finite number of write cycles, so the controller constantly moves data around to spread the wear, retires cells that have gone bad and keeps a private translation table mapping what the camera thinks it wrote to where the bytes physically ended up.
That arrangement is invisible while it works and it is the whole story when it fails. If the controller stops answering, the memory underneath can be in perfect condition and still be unreachable, because nothing outside the card knows the translation. Rescuing SD card data from that position means addressing the memory directly and working the mapping out again from the patterns in what comes off, which is slow, skilled and entirely different from plugging a card into a reader.
It also explains why cards die without a sound. A hard drive gives you clicking, slow starts and warning noises. A card is silent right up until the moment it is not, and the failure is usually total rather than gradual. Nobody gets a fortnight of hints in which to make a backup.
Pulling a card out while a light is still flashing is the single most common cause of a corrupt card. The camera has told you the shot is saved, but the file system entry may still be sitting in a buffer, and interrupting that leaves a card that lists most of its pictures and loses the last few, or one that will not mount at all.
Filling a card to the very last megabyte is the second. Wear levelling needs spare room to shuffle blocks into, and a card kept permanently at ninety-nine per cent full has nowhere to move anything. Formatting in the camera rather than on a computer avoids a third class of problem, because a camera writes the layout it expects to read; a Windows format on a large card can produce a structure the body will merely tolerate.
Then there are counterfeits. A great many cheap high-capacity cards are small cards with the firmware rewritten to report a size they do not have. They appear to work, right up to the point where the writing wraps around and quietly destroys everything recorded earlier. If a 512GB card cost eleven pounds, that is very likely what happened, and it is worth testing a new card with a capacity checker before it is trusted with anything.
A full-size SD card has a board inside it with recognisable components. Most microSD cards do not: they are monolithic, meaning the controller and the memory are moulded into a single sealed block with contacts on one face. There is nothing to unsolder and no board to lift a chip from. Working on a monolith means finding the test points buried in the package and reading the memory through them, which is careful, uncertain work.
That is worth knowing before a microSD out of a phone, a drone or a dash cam is written off, and it is also why the honest answer on a monolith is sometimes that the diagnostic will decide. The diagnostic still costs nothing. What it does not do is promise a result on a card that has been bent in half.
Cards sit in the flash band: £250 + VAT, whatever the capacity and whatever the format. Full-size SD, microSD, SDHC, SDXC, CompactFlash, XQD, CFexpress, Memory Stick and the rest are all the same figure, and so is a USB stick. There is no per-gigabyte charge and no scale that rises with how many photographs come back.
For the sake of the whole picture, the other bands are: a single hard drive or SSD £300 + VAT; a CCTV or DVR recorder drive £400 + VAT, as are BitLocker and other encrypted volumes; arrays, NAS boxes and servers from £500 + VAT depending on member count; forensic investigation with a written report £800 + VAT, or £400 + VAT for a binary image with deleted-file extraction and no report.
Logical card jobs — deleted pictures, a formatted card, a corrupt file system, a card asking to be formatted — carry no fix, no fee. Chip-level work does not, and neither do electronic or mechanical failures, DVR jobs or forensic jobs. Those exclusions are published rather than sprung on anybody at the end. The free diagnostic closes two working days after the card is booked in, and a card recovery is normally finished within two to four working days of you approving the figure.
A card weighs nothing, which is exactly the problem: a bare card in a paper envelope goes through the sorting machinery and arrives in pieces. Put it in its plastic case, or tape it between two pieces of stiff card, then send that inside a padded envelope. Do not send the camera, the drone or the dash cam. The card is the whole job.
Add a note saying what the card came out of, what it was doing when it stopped, and roughly what you are hoping to get back — a wedding, a survey, a fortnight in Portugal. Knowing the file types and the approximate date range genuinely speeds up the sorting at the far end. The address is Oxford Data Recovery, John Eccles House, Oxford Science Park, Robert Robinson Avenue, Littlemore, Oxford OX4 4GP, and drop-offs are taken there on weekdays between 9:00am and 5:30pm if you would rather drive it down the M40.
The cards arriving from Coventry and Warwickshire are not, on the whole, holiday snaps. They are the drone footage from a site survey at Ansty, the photographic record of a restoration job, the dash cam clip somebody needs for an insurance claim on the M6, the card out of a camera at a wedding in Stratford, the trail-camera and CCTV cards from a yard in Nuneaton. They matter because they cannot be taken again, which is the same reason nobody ever has a second copy.
If the card is still in the camera and still reading, the single most useful thing you can do before anything else is copy everything off it, exactly as it is, onto a computer. Not sorted, not renamed, not edited. Copy first and tidy afterwards, because a card that is behaving oddly today may not be readable at all tomorrow.
Every further attempt in the camera or the reader costs you a little of what is still recoverable. Post it in and let the diagnostic say where you stand.
Parcels are how nearly all of this work arrives, and they come from a good deal further afield than Warwickshire. Padding and a tracked label treat a poorly drive better than a week of being carried about, and a box handed to a courier on a weekday afternoon usually reaches the Oxford bench in the morning.
As a rule the storage comes out and the machine stays where it is. That applies to a laptop, a tower, an iMac and to the recorder sitting under a counter. Taking equipment apart is not something this bench does, and a repair shop will free a drive in a few minutes. Two things go the other way: an external drive stays sealed inside its own case, and a NAS travels as a complete unit with its disks still in their bays. A Fusion Mac is a third case — both of its drives come out and travel together, each one labelled. The single situation nobody can work around is memory soldered flat onto a mainboard, which is how Apple Silicon Macs and a good many slim laptops are built: if the storage will not unbolt, there is no parcel to send.
↓ Print the shipping & booking-in form (PDF)
Put Oxford Data Recovery on the label. From Coventry it is roughly fifty-five miles straight down the M40, about an hour if you would rather drive it in than post it. Either way you are told the moment it is logged, and the free diagnostic finishes two working days later.
Unsure what ought to go in the box? Ring 0800 689 0668 before you seal it, or work through the free online diagnostic and let it do the asking.