MY BOOK 1.5 TB Essential not recognized

Hi user1711, welcome to the WD Community. Sorry to hear you cannot access your files. In most cases it is not recommended to try repairing the drives yourself since this can damage your information further. Before trying anything else I recommend you to contact support directly for assistance. 

http://support.wdc.com/country/index.asp

There are also some Community users with knowledge on how to repair drives, but again this is not recommended. 

http://community.wd.com/t5/External-Drives-for-PC/connected-wrong-power-supply-to-3TB-WD-My-Book-Essential-any-way/m-p/841138#M22725