WD Passport not recognized

Hi, I have 2Tb WD My passport not recognized on my computer.

Light is on, blip on computer as well, the disk is attempting to run several times but it is not visible.

I use a PC, windows 7.

Any suggestion?

Thanks Luciano

Was this hard drive working before on the same computer? Have you changed the USB cable? Is the hard drive detected in Disk Management?