How do I recover files destroyed / deleted external hard disk

WD External Drives External Drives for Mac
1

A year ago I travel in USA and shot video, two weeks ago my cousins ​​wanted to see the video  from Disneyland so i past All Videos from Disneyland to new folder , someone accidentally unplugged the cable and then the files was damage/destroyed/deleted … I mean they are look they are there but
All size 0 mb and I do not know what to do :-(

Now my question is:
Is it possible a reconstruction of an earlier time before this happened or is there a software that can recover?

can i recover them ? Or files and memories completely lost? :-(

Hard disk is an external WD hard disk 
And the computer is a MacBook Pro
If it matters

2

Hi, probably the data is corrupted, try using a data recovery program.

3

before going for data recovery see if you can repair the partition on Disk Utility

First Aid works in this type of situations