Don't see my external hard drive in disk management or on computer

Tried just about everything but I still can't seem to get my external hard drive to show up in my disk management or computer. It say it's installed and ready to use but I don't see it.. only in the device manager and in devices and printers I can see it.. but nowhere else.. I'm working with windows 7 upgraded from windows xp but has be downgraded which was originally windows vista I think.. A friend gave me a computer and I had it upgraded.. can any one help me get my computer and external hard drive straight. Thanks.
Yes.. I've tried that.. except mine doesn't show my external hard drive in the disk management at all.. disk 0 which seems to be my main drive is on basic 232.83 GB online.. disk 1 and so on downt to disk 5 says no media then there's the cd - rom 0 dvd no media as well.. that's all that it say in my disk management. But in device manager I can see my hd plain as day.. tried to upload a picture but it's sayin it's too big to send.. I've tried Alot but can't figure it out
Yes I'm using USB.. I tried all the USB ports and it's still the same.. I have a OWC Mercury Elite Pro Mini external hard drive.. If I right click on disk 1 in my disk management and go to properties.. it says my hd name OWC elite mini. But why not on the actual disk.. it just say Disk 1, Removable ( I ) NO MEDIA