Hi,

In order to resolve this problem, follow the below steps:

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.
There are three ways to update a driver:

• Use Windows Update. You might need to set Windows Update to automatically download and install recommended updates.
• Install software from the device manufacturer. For example, if your device came with a disc, that disc might contain software that installs a driver for the device.

• Download and update the driver yourself. Use this method to install a driver that you download from the manufacturer's website. Do this if Windows Update can't find a driver for your device and the device didn't come with software that installs a driver. The Windows 7 Compatibility Center website lists thousands of devices, and has direct links to driver downloads.

Make sure you set Windows to install updates as well by following below steps:

1. Open Windows Update by clicking the Start button . In the search box, type Update, and then, in the list of results, click Windows Update.
2. In the left pane, click Change settings.
3. Under Important updates, click an item in the list.

   

4. Under Recommended updates, select the Give me recommended updates the same way I receive important updates check box, and then click OK. If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
   

   You can also allow anyone using your computer to install updates by selecting the Allow all users to install updates on this computer check box.

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.


I hope this helps.

Regards,
Lokesh