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I am trying to help a friend who is very concerned that she has just lost all of the data on her 32GB SanDisk microSD card. I told her I would post this and see if anyone could offer help.

Here are the details:

  1. The SanDisk microSD card is less than two years old. Probably only about a year old. The store will take it back, but that doesn't really help. She wants her data.
  2. She used the card in her Samsung Galaxy S4 smartphone for over a month. The phone was never exposed to water or temperature extremes.
  3. Today, her phone suddenly said something like "Your SD card is blank or an unsupported format".
  4. Her phone was then unable to read the SanDisk microSD card at all.

Here's what she has tried:

  1. Rebooting her phone. Had no effect.
  2. Taking out the SanDisk microSD card and putting it inside a full-size SD card adapter, and inserting it into a Windows 7 SP1 computer. The computer did not recognize its presence at all.
  3. Putting the SanDisk microSD card into a USB 2.0 external card reader and inserting the card reader into a USB port on a Windows 7 SP1 computer. The computer recognized the card reader and installed drivers for it. The card reader shows up as 'Removable Disk' in Windows Explorer. Clicking on 'Removable Disk' in Windows Explorer results in the error "Insert disk: Please insert a disk into the Removable Disk".
  4. After trying #3, tried opening the 'Removable Disk' in FreeCommander. Doing so results in the error "The device is not ready".

She does not have access to a linux box, but does have access to her Android phone.

What can she do to recover the data on her 32GB SanDisk microSD card?

  • Could you post a screenshot of what you see in the Disk Management control panel when the card is inserted in the card reader? If you see the full size disk but the partition is missing you might be able to use TestDisk to try and recover the partition or data. – Mokubai Dec 23 '14 at 7:03
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    @Mokubai The "blank or unsupported" from the phone is promising, but the "insert disk" is not. That's why the first step is to find a reader that can detect it - then there may be a chance. Always take an image, e.g. with ddrescue, before trying other recovery operations - don't squander what might be the one chance to get data off it. Then just follow standard HDD recovery procedures from the dd image. I might write up more later, but it'd echo existing HDD data recovery questions. – Bob Dec 23 '14 at 7:17
  • @bob good point. I have a couple of modern computers that have inbuilt card readers that can't understand new SD cards but my laptop can read them. Finding a machine that can detect the SD card at all is the first step. – Mokubai Dec 23 '14 at 7:25
  • If the data is very important, I think it is possible to dismount the SD card, get chips from inside, mount them on other card of the same model and read the information. But this can be made by company or skilled specialist, not by everybody. – i486 Dec 23 '14 at 10:33
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    @i486 If the card is indeed a microSD card, there really isn't any "inside" as much as there is an epoxy coating around bare chips and a thin interposer layer with interconnect and the gold pads. Washing the epoxy off is not something easy to do in a way that will leave the chips functional, even given all the right tools and chemicals. – RBerteig Dec 24 '14 at 2:25
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You could try pressing the card together (in case it came a little loose?) and maybe cleaning the contacts with a little bit of isopropanol on a swab. But I really wouldn't expect any results, and at best you might manage to read some of the data off before it dies again. I would not recommend opening it up under any circumstances - that will not help recovery any, and it will likely cause further damage.

You could also try various alternative readers - if you manage to find one that can at least expose the card as a block device, then you can take an image of the data (while recovering useful data from an image of damaged media is a whole other exercise - it's still better than where you are now).


Sometimes, there just isn't anything that can be done. If the data is very important, you could consider professional data recovery services (do they even exist for SD cards?), but they'd be very expensive. Otherwise, she might just have to accept the loss and try to recreate what she can.

When a storage device becomes physically unreadable, undetectable even, you can't go through the normal home data recovery steps (take image, scan for what files you can, etc.). With a mechanical drive, at least common failure modes are partial, so you can at least read something. With the nature of NAND storage, I can think of three possibilities:

  • You've lost the controller. The flash chip itself might still be readable, but reassembling the data from it will be a long and arduous task. This is not doable at home, and requires expensive, professional tools and expertise. (If you had the equipment to solder tiny chips (source) and read NAND flash, I suppose you could attempt this yourself, but you're more likely to accidentally destroy it.)

  • You've lost the flash chip itself. In this case, I don't think there's anything you or anyone else can do. It would be even harder to recover than a lost controller.

  • The card is physically damaged, but the controller and flash memory are intact. This is probably the best you can hope for. Again, with how small and fragile the card is, there isn't much you can do at home - but the chance of professional recovery is far higher.

The problem with all these is they require very expensive and still uncertain services to even attempt a recovery. Is the data worth that much?


Perhaps the best thing to do is to treat this as a lesson on backups - always have at least one extra copy of any data you can't afford to lose. The more important it is, the more copies you want, stored separately from each other.

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    Thanks. She took your advice and tried squeezing it between her fingers. Unfortunately, it didn't help (but didn't hurt!). Wait... Wait... Wait... she just did it again, and Windows is recognizing the card!!!!!!!! Tears of joy!!! Now we can celebrate two miracles on Channukah!!! Thank you!!! Shalom!!! – RockPaperLizard Dec 23 '14 at 8:19
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    Good news! Now go buy another SD card and throw the damaged one away, not worth risking that again. – Robin Whittleton Dec 23 '14 at 9:14
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    @h.j.k. If there's any poor solder joints, for example, squeezing can get them to temporarily reconnect. This is a very temporary thing - evacuate your data and never use that card again. – Bob Dec 23 '14 at 10:23
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    It never would have occurred to me to try to squeeze the data out like this. Wow. Will wonders never cease? – BrianH Dec 23 '14 at 15:40
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    +1 for "Perhaps the best thing to do is to treat this as a lesson on backups". – Guntram Blohm Dec 23 '14 at 17:07

protected by bwDraco Dec 26 '14 at 22:48

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