can't find storage device

some time ago I installed a extern Jukebox 20G storagedevice and used to
store large files, music and backups. One day I took the harddisk out and
put it back in again. The following happened:
1 The device says that there are no files on the harddisk although there was
a lot of info stored on it
2 When I connect it the computer (as I did before), my system tells me that
the device works correctly but there is no way I can find it in my
directory! I can't find it so I can't acces it.
Before it gave me a "F" harddrive that I could acces. Now there's nothing
but the system recognizes the device and states there is no problem with it
nore is there a problem with the USB.
Can anyone help me?



walter