USB disk & keys won't show

Hello,

I have a USB external disk and a few USB keys and for some reason it wont show up anywhere in my computer. I've tried everything everyone says by looking up in the Manage section of my computer then Disk Management. I've tried shutting down my computer, unplugging it, wait for a few seconds and even minutes and nothing. It says that everything works fine and even sometimes all of my USB devices will show up, Keys and my external disk then after a few min of playing in it, everything stops and I can't go in them anymore.....Even in the device Manager it says that everything is working properly but I can't see them anywhere.....I know that they work just fine cause like I said, they show up some times and I can open them at a friends computer, ps3.....

I really hope someone can help me here, cause I'm an idiot and I have everything important on thoses damn devices lol, but no more :P if I can get them to open and not crash when I need them.

Thanks all !!