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i bought a new android phone and i inserted a 32gb sdhc card that i used in my htc on it. it works well for 3 days , suddenly it showed me a message unsafe to remove memory card. then i reinserted the memory card but it is not working . then i inserted it on my htc sensation same thing happens nothing is showing. then i used a card reader to read the memory card in pc but my pc not showing any thing. i tried different memory card all that is working well in my pc and also in my phone. the 32gb is not reading any where. how can i recover all data from it. my important data is on my sd card can u please help my to sort out this problem . please help me kindly

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@Chahk Difference seems to be that in this case here the card is not even recognized by the PC (prejoy: could you please clarify this? Does your PC at least recognize the card as such, even if not "showing anything"?) –  Izzy Apr 22 '13 at 21:25
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marked as duplicate by Chahk, roxan, t0mm13b, Bryan Denny Apr 24 '13 at 13:27

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Sounds like a damaged flash card, or a broken file system.

If it's a Windows PC, insert the flash card, then press WinKey+R (or go to Start -> Run) and type diskmgmt.msc, then click OK. You should be able to see your flash card within the list, and see if it's got any partitions listed.

Disk Management

In this case, I've got a 2GB SDHC card plugged in, which shows up as a 1.89GB device with a FAT partition that fills the entire card.

You may find one of several things:

  • The device doesn't show at all. If this is the case, then sorry but your data is gone. Short of some very expensive recovery techniques, you're not getting it back.
  • The device shows but there are no partitions. This usually means that your partition table is broken or unreadable.
  • There is a partition, but Windows doesn't recognise the file system (it might show as RAW or Unknown). In this case, your partition header and/or file system headers are broken or unreadable.

In the latter two cases, you may be able to recover some data, but expect corruption and missing files. This is especially problematic on flash cards where the cells that store wear-leveling metadata have become corrupted, since mapping the logical cell address to the physical cell becomes impossible. The card will have to be replaced too, since it is clearly damaged.

Recovery can be done in several ways:

  • There are commercial and freeware tools that try to do this. Google for "SD card recover" and similar terms - I'm sure you'll find many results.
  • Use a low-level tool or command like dd to read a full copy of the SD card, then use sfdisk to find the offset and size of the file system and extract it, then mount it. (see this blog post)
  • If all else fails, use a tool such as binwalk to manually extract files from the drive binary image. This is tedious and rather involved, but can recover data that automated tools miss.

In future, I highly recommend keeping backups!

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Very good and comprehensive answer, Polynomial! +1 from me. @Prejoy: in those "latter two cases", please also follow Chahk's "duplicate" link, and you might also read the data-recovery tag-wiki for first-aid and hints. What still is unclear to us is whether your card falls into the "first category" (i.e. your computer does not even detect the card as such). As Polynomial correctly pointed out: apart from expensive recovery companies, there's nothing more you could do. –  Izzy Apr 24 '13 at 10:40
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