Started losing data and then computer wouldn't boot up

I noticed a couple of days ago that when I tried to retrieve data from my Passport that older files were blank. I turned off the computer thinking a re-boot might help but the next morning it was the same. The only data I could access was the most recent uploads on the drive. Today my iMac wouldn’t boot up at all until I unplugged the Passport.
I also have the High Sierra 10.13.4 update. Could that be the cause? Will I be able to get my data back?

Hi Ken3,

Maybe you should try contacting WD’s Technical Support about this.

To Contact WD for Technical Support

The link below will allow you to call support.