Mybook 1140 essential not working

ever since i bought it, when i plug it into my pc usb port, it just blinks, its a fast blink…im using windows 7, and when i check the devices section, i can see it, but cant see a drive letter in my computer…now i have 2 of these, but only have a problem with one…please help fix, i need this drive like yesterday

Hi and welcome to the WD community.

If you have two of the same My book model connected to the same computer, but only one of them is recognized, you might be having a signature collision problem. See if the steps from the link below help.

Only one drive is seen when connecting two WD external drives of the same size to a Windows 7 or Windows 8 PC

If the easy way doesn’t work out here is a more permanent fix