Western Digital Passport 1 TB -- Video Files not playing

Dear Friends,

I am having a problem,  I am having huge collection of video files in my external hard disk. Of late my hard disk shows the files in the directory.  whenever I tried to play video files, some files play after so much time, some doesnot respond at all.  I request that my problem may kindly be solved.  I tried recovery softwares also but of no avail.  I have around 470 GB of data.  Request for solving my problem 

Hello, you can first try running a test with DLG to rule out any possible hardware damage, if the test completes successfully the problem could be related to data corruption. Try backing up all files and then format the Passport to use it again normally. Check the link below for the steps to run a DLG test. 

How to test a drive for problems using Data Lifeguard Diagnostics for Windows