Quick answer
First stop writing anything to the card or USB and make a full image copy of the entire media with a disk imaging tool, then attempt recovery. If the media is not recognized at all or shows signs of physical damage, do not try it yourself, because every write and format reduces the chance of rescuing your data.
How to recognize the problem
- The computer shows a message that the disk needs to be formatted before use
- The card or USB appears in the system, but folders are empty or will not open
- Copying photos stops with an error or files appear corrupted
- Windows reports a read error or a disk check loop
- The phone or camera does not recognize the card, but it behaves incorrectly on the computer
Most common causes
Interrupted write or removal without safe eject
If the card is removed while the system is still writing data, the file system and allocation table can become inconsistent, so folders are not visible even though the data is still on the media.
Poor quality or worn-out flash memory
Cheap cards and older USB devices have a limited number of writes and can switch to read-only mode or start returning errors on individual sectors.
Physical damage to the controller or connector
A drop, moisture or a bent USB connector can damage the controller, causing the device to disappear from the system or overheat during use.
Faulty card reader or port
Sometimes the problem is not the card but the reader, extension cable or USB port, so the same media works correctly on another computer.
Viruses and unexpected interruptions
Malware that creates shortcuts or interrupts work during copying can leave the file system in a state that Windows interprets as corruption.
Step-by-step fix
- 1
Stop all writing and disconnect the device
Immediately stop copying, deleting or formatting. If the device is connected, use the Safely Remove Hardware option in the system tray, then unplug it. Do not run
chkdskright away and do not accept the offer to format, because both procedures change the contents of the media. - 2
Check whether the problem is the reader or the port
Try the card in another reader, and the USB in another port, preferably directly on the motherboard without an extension cable. If the media is recognized on another computer, do the recovery from there. Write down the exact device model and size, you will need them later.
- 3
Make a copy of the entire card before recovery
Install a trusted disk imaging tool, for example
Win32 Disk Imagerorddrescue, and save the entire device, not just the partition, to an IMG file on another disk. UseHxDonly for viewing. Always do recovery from that image, never directly from the original. This keeps the source media untouched. - 4
Try reading without repairing
Open the card in File Explorer and if the folders are visible, immediately copy everything you can to another disk. If copying fails on individual files, skip them and continue. Do not open files directly from the card, because reading can put additional strain on damaged sectors.
- 5
Use a data recovery tool
Run a trusted recovery program, for example
Recuva,PhotoRecorTestDisk, and point it to the saved image if the tool supports it, or to the write-protected card. Choose the deep scan option if the quick scan finds nothing. Save the results only to another disk, never to the same media. - 6
Check the file system integrity
If the card reads but Windows reports errors, first save a copy and extract everything you can. In
Command Promptrun as administrator, typechkdsk X: /fwhere X is the card letter. Do this only on a copy or when you have a verified backup, because the repair changes the file system structure and can further damage the data. - 7
Wait with formatting until the end
Format the card only if you are sure all data has been rescued or if the media is empty anyway. A quick format is less invasive than a full one, but it also changes the file system. If the card still produces errors after formatting, consider it unreliable and replace it.
When it is better to stop and call an expert
If the card does not appear at all in Disk Management (Win + X > Disk Management), if the USB overheats or the computer reports a controller error, it is probably a hardware failure. In that case do not open the casing and do not press the connector, because you can permanently damage the memory chips. For business data from a camera or voice recorder card, professional recovery is more worthwhile than the risk of losing everything. If the data reads but the files are corrupted, first check whether you have a copy in a cloud service or on another device, because restoring from a backup is always faster and safer than recovery from faulty media.
How to prevent it
- Always use the Safely Remove Hardware option in the system tray before removing a card or USB device
- Buy cards and USB drives from trusted manufacturers and avoid suspiciously cheap models
- Keep at least two copies of important photos, for example on the computer and in a cloud service
- Occasionally check the health of the media with the manufacturer's tool and replace older devices in time
When to call a professional
Contact IT support or a recovery service if the media is not recognized, if it overheats or shows other signs of hardware failure, or if it involves business data you must not lose. In those cases every further attempt can permanently destroy the chance of rescuing your data.
IT infrastructure maintenance · Servers, networks, backup, security and helpdeskFAQ
May I format the card if Windows suggests it?
No, do not accept formatting until you have saved a copy and attempted recovery. Formatting changes the file system and reduces the chance of finding the photos later, especially if you choose a full format.
Can I recover files from a card that is not visible in the system?
If the card is not visible even in `Disk Management`, the problem is probably hardware and software tools will not help. In that case the safest option is to contact a data recovery service, without further connection attempts.
How much does data recovery from a corrupted SD card cost?
The price depends on the type of failure and the amount of data, and professional services determine it after an inspection. For home photos, first use free tools and a copy of the media, and call a professional when those procedures do not give results.