Welcome to the community, @kittymama666!
You should be able to fix this particular error by logging into Windows as an Administrator and then make the hard drive online by right-clicking on the volume in Disk Management. If you still face issues, try
taking ownership of the HDD in Windows. Afterwards, go back to Disk Management and attempt to make the external drive Online again.
If it's a brand new HDD, you should be able to make the HDD accessible in Windows Explorer (MY Computer/This PC) by
initalizing it first, and then
partition & format it.
Hope this works. Let me know how the troubleshooting is going!
SuperSoph_WD