There are few things why your SD card not recognized on Android. Hope your card is not corrupted. You can try another SD card and to see if its recognized or windows is missing a driver. Try your SD on another windows based PC or try on a Linux system.
First you need to confirm your PC’s driver. If your PC does not detect the SD card, the problem may be related to the driver. You can try to update it.
Step 1 – Check you PC Driver
• Open the “Computer” and select the “System Properties” tab.
• In the task bar on the left click “device manager”
• Next to ” USB controller “click the” + “next door and you should see a yellow exclamation mark.
• All you need to right click and choose “update driver software” then “automatically search for driver software online “
• Wait for the driver to be installed and reboot your computer.
If it doesn’t work there maybe another problem in your SD card. sometimes computer cant read 4GB or higher SDHC card or digital camera can’t read 4GB SDHC card as well. For this Problem follow the structure bellow.
Step 2 – SD and SDHC card
SD and SDHC compliance
If your computer’s internal card reader works with 2GB (or lower) SD cards but fails to read a 4GB (or higher) SDHC card, then the computer’s internal reader is not SDHC compliant.
This same logic also applies to digital cameras, if the digital camera reads 2GB (or lower) SD cards but fails to read a 4GB (or higher) SDHC card, then the digital camera is not SDHC compliant.
SD and SDHC specifications
The initial SD card specification defined the interface for cards only up to 2GB capacity. The subsequent SDHC specification was developed to provide increased capacity of 4GB – 32GB cards. Computers and other products purchased before 2008 may not be SDHC compatible. Computers and other products purchased before 2007 are not SDHC compatible.
Verifying the card reader slot
If the card reader slot on your computer does not have the SDHC logo, it is most likely not SDHC compatible and will only read cards up to 2GB capacity.
Other options you can use to read files on your SDHC card
If your computer’s card reader is not SDHC compatible, you have 3 options available:
1. You can connect your camera (or other device) that works with SDHC to your computer using a USB cable that came with the camera. You should be able to transfer files to the computer this way.
2. You can contact you computer manufacturer to see if they have a free firmware update for your model that will make it SDHC compatible
3. You can buy inexpensive SanDisk SDHC card readers that will connect to your computer’s USB port.”