WD external hard drive won't turn off

[computer novice]

Hi

I have a Western Digital external hard drive (my book) that won't turn off when you press the button on the front of the hard drive this wasn't always the case it has just started to happen in the last day or so after I reformatted my PC when I reformatted the PC I had unplugged my WD external hard drive so as not to interfere with it any suggestion are welcome maybe I have to reset to factory setting but can't see a way to do that.

Thanks

Computer Novice

[kodi]

Probably a faulty switch. Is it still under warranty?

[computer novice]

Yes thankfully has a 3 year warranty