Hard Disk Won't Initialize,Computer sees it but wont do anything

so I've been searching or quite a while now and haven't found anything that seems to help. I'm trying to get the files of my comstar 500gb external hard drive. It worked not to long ago but now i can access anything. It doesn't show up in my computer but does in disk management. When i open it asks me to initialize and when i click on either of the two option i can choose i get the response "Incorrect Function" When i click properties is states that everything is working normal but it wont open. I've tried using testdisk but my hard drive doesn't show up. I can hear it turning, i even opened it up and can see the arm moving. I states when i click on it that it has 0gb, any help is appreciated