USB Drive won't appear anywhere else but in disc management

Hello,

I have plugged an external hard drive into my computer which won't appear anywhere else but in disc management. It has a letter assigned to it already although I did change it to see if that would fix the problem (it didn't). Disc management suggests that there is no media content (there is - all of the data from my previous computer!) It is so frustrating as it was working earlier with no problems. It still makes the noise that it should when I connect it but it doesn't load anything. When I go to device manager and troubleshoot it - it says that everything is working correctly but it won't open or show me any of my files. Please help!