New Latitude sees external harddrive, but not files on it.

New Dell Latitude laptop-replacement for desktop. i have Toshiba external HD with files on it that show up on laptop in Devices, but I cannot see or move files on it.  External works on other computers. It's not the external harddrive. Been thru Dell, Toshiba (harddrive manufaturer whom I will never use again for anything because of lack of support) How do I make external harddrive useable? I got it specifically for this and it has all my backup! Thanks for any help. I'm getting desperate. Jann