1. Check if the device is getting detected in device manager. Follow the steps to go to device manager
i. Click Start, type devmgmt.msc and press enter.
ii. Search for the name of the device
If the device is not getting detected in device manager, then check if it is hidden device.
i. Click show hidden devices under View
ii. expand all the nods under device manager
iii. There would be many grayed out entries in device manager uninstall all the grayed out entries under all the nods and then restart the computer and plug the external device to the computer and check if it works
2. Install the latest drivers from the manufacturer website and even make sure the driver is compatible with the version of operating system installed on your computer. check if it works
Link: http://windows.microsoft.com/en-us/windows7/Update-a-driver-for-hardware-that-isnt-working-properly Install the driver in Compatibility mode: http://windows.microsoft.com/en-us/windows7/Make-older-programs-run-in-this-version-of-Windows
3. Check with any other another SD card if it is getting recognized or detected or you may even check if the same SD card is getting recognized or detected on other computer
Thanks and Regards:
Samhrutha G S - Microsoft Support