You insert an SD or microSD card and nothing appears: no popup, no drive letter, and no Finder item. This applies to SD, microSD with adapter, SDHC, and SDXC cards used with built-in or USB readers on Windows and Mac.
Does This Affect You?
An SD card that does not show up is usually not seated correctly, locked, loose inside a microSD adapter, unreadable because of corruption, or detected by the system without being mounted normally.
Check the Physical Basics
Start with the card and reader.
- Remove and reinsert the card firmly until it clicks or stops.
- Check the lock switch on full-size SD cards or adapters and slide it to unlocked.
- For microSD adapters, make sure the microSD card is fully seated inside the adapter.
- Try another reader, such as a USB reader instead of the laptop slot.
- Wipe gold contacts gently with a dry lint-free cloth.
Check If Windows or Mac Sees It but Does Not Show It
The card may be detected below File Explorer or Finder.
- On Windows, open Disk Management and look for the card by approximate size.
- If it appears without a letter, right-click and assign a drive letter.
- If it shows RAW or Unallocated, the file system may be corrupted. Do not format yet if you need files.
- On Mac, open Disk Utility, select the card if it appears, and click Mount or run First Aid.
- If the card is absent from Disk Management and Disk Utility, test another reader and computer.
If the card is corrupted and files matter, stop using it and try recovery software before formatting. Cameras can sometimes read or repair cards they formatted, so test in the original camera. A card that fails across readers or reports a much smaller capacity may be counterfeit or physically failed. SD cards are inexpensive and usually replaced rather than repaired after data recovery is handled.
Sources
- SanDisk – My computer does not recognize my memory card (2025)
- Microsoft Support – Fix a memory card that is not recognized (2025)
- Apple Support – If your Mac does not recognize an SD card (2024)