Welcome to the forum.
Can you give us the full details of those files?
Can you tell us about the external HDD, and especially its connection type?
Have those files been used in any Project, or are they just in an Organizer Album?
Good luck, and please let us know a bit more.
Thanks for interest, but files restored. It appears you have to invite files back through elements rather than trying to open from the hard drive,
Yes, in transferring files/albums/projects or restoring any thing related to PRE or EO, it works better if done from the application itself. Great that you figured it out.