This sounds like if the drive was already dying and Explorer locked up because of that.
If it is a USB attached drive Windows may still see the USB-SATA chip inside the WD housing (which gives you device plugged/unplugged messages), but can't see the disk itself anymore.
Anyway: Shut down the computer and if the WD has its own powersupply disconnect that too.
Then start everything back up in this order: Laptop first. Then WD. Only then plug the WD back into the computer.
If you are lucky Windows will recognize the drive again. If so have Windows check it for errors befor eyou do anything else first. (Windows may even suggest that, but if it doesn't you have to do it yourself.)
If it doesn't come back you can try it on another computer. You can also open up the housing and take the actual disk out and hook that up directly to a computer by SATA. (In case the USB-SATA converter chip is broken, but it doesn't sounds likely from your comments that is the problem.)
If you can access the content of the disk copy your important files to another medium immediately. I would consider this disk to be compromised and wouldn't trust it for important data anymore.