WD External hard drive problem from no where?

Ok. Well my external hard drive is about 3 months old.
I have videos, pictures and my itunes library on it.
It has been working without a flaw up until now.

I plug it in, type in password, click the vid or pic I wanna view and i get "discovering" or "cant find file/cant read file or cant read file because device error I/O."
Also, after I try to close the forever loading/discovering video it "stops working" and crashes explorer and explorer doesnt come back up until I unplug the drive.
It seems to not even want to load the picture folder at all.

????

I tried defraging it, scanning it with malwarebytes and McAfee with no avail.
It insists everything is fine.

Someone help? All my stuff is basically ON the harddrive but I cant use them
Also, while freaking out thinking I might lose everything, I tried moving/copying all my stuff to my laptop and only SOME things would transfer while other things will display "cant find or discovering.."

Its weird because it was working fine the day before and now its gone to hell overnight. I havent installed anything new on my laptop since. But on the drive i download stuff constantly so I can't really tell if all this started after I downloaded something or not.

Your first priority - before you start doing anything with the external drive - is to copy all data from it to another drive.

Try to access your external drive from another OS to do it. The following link should help.

Lucid Puppy way to recover files from a non-bootable computer

Once you have copied all data, run the diagnostic program as suggested by essenbe.

I would take any I/O error message seriously.