My Book Essential power off

I’ve used My Book for 3 years, Everything fine, until today, no power light is shown.  

I try to connect ac adapter many times but nothing happen.  Do I have to change ac adapter ? Or ??? My data, pictures are safe or lost ?

I cannot say if your drive is OK or not.

Measure the voltage at the adapter tip. 

It should read 12 - 12.5 volts.

If you don’t have a multimeter, take it to someone that does.

Failing that, just get a new adapter. Ebay has tons of them .

Remember to sort from cheapest including delivery, and you will find hundreds of inexpensive replacement power adapters.

The only other option is to send everything to someone that can do the diagnostics for you.