Try to unplug it and connect it with another port on the computer, if it doesn't work neither, it may be bad. Or you can try to create a new partition and give a new drive letter to the external hard drive. Check here to create partition with free third party software. How to Make Partition and Create Partition on Hard Drive
Answers & Comments
Try to unplug it and connect it with another port on the computer, if it doesn't work neither, it may be bad. Or you can try to create a new partition and give a new drive letter to the external hard drive. Check here to create partition with free third party software. How to Make Partition and Create Partition on Hard Drive
If it is not being recognized you can always try and assign it a different partition letter:
Hard Drive Not Showing Up In My Computer How To Fix It