On 2014 when I check my WD 2TB My Book Essential, there was warranty

Serial Number: [[DELETED]]
Now when I check, it shows Invalid serial.
This WD 2TB My Book Essential is locked. I never kept a single password, why it is locked?
Please help…

Is it because of security slot, or ???

I recommend you contact WD support for assistance with this.

http://support.wdc.com/contact.aspx

Contacted them but my Warranty over @ 2013