Next could be "have a cup of coffee" and/or "go take a shower" -- preferably not both at the same time, though.
More seriously, are we supposed to *guess* what is your system -- distribution and version --, what are the exact name of the files, what did you (try to) do exactly and what do you want to do ?
OK, let's guess for now.
I suppose that:
- you have Linux installed
- your external disk drive is mounted
- you would like to find your backup files on it, may be to copy it somewhere else
- you do not know how to find a file under Linux
Basically you have at least two ways to find a file in Linux using a terminal.
1) As root, issue the command
to make a database of all your files and their location on the (then mounted) disks. It will take a few minutes to run. Wait till you get the prompt back.
2a) If you know the exact file name, issue the command
locate -i <filename>
If you are lucky the ouput will be the location of the file.
2b) If you know only part of the filename type
locate -i "*<known_part_of_the_filename>*"
instead. Don't forget the quotes.
Still as root, issue one of the following commands:
find <mount_point_of_your_external_hard_disk> -iname <filename>
find <mount_point_of_your_external_hard_disk> -iname "*<known_part_of_the_filename>*"