"Attempting to copy to the disk "NAMEOFHDD" failed. An unknown error occurred. (-69)"

"Attempting to copy to the disk "NAMEOFHDD" failed. An unknown error occurred. (-69)"

I am attempting to copy an album of songs into my iTunes, by dragging and dropping, as I have done 1000 times before. The files run perfectly, as I have played them in a different media player to check if the files were legit. I have only found this particular error referenced when people try to sync their iPods. Mine isn't even connected, just in case. The problem just started tonight. I am using Windows 10, but don't believe it is the problem as I have dragged and dropped on this OS before already. Any suggestions, that do not have anything to do with my iPod?
Thankyou.