Why won’t my computer list or open my 500 g external hard drive

I bought a external hard drive I put movies on it and some work data, I plugged it into the usb port thinking it would play the movies on my Blue Ray player, it didn’t (a storage stick will so I thought this would work the same way) when i plugged it back in to the USB port on my computer it no longer comes up as an icon in my computer and if i go into devices it says everything is working fine but the external is not recognizable by the computer, it will not open .