My passport stopped working

My WD My Passport Essential External HD has been working fine for the last 4 months from when I purchased it. It is a 2 GB version. All of a sudden it will not show up when I put the USB cable into the USB slot on my laptop, other USB devices self install and show up correctly. I have even purchased a new USB cable and the same thing happens. The device seems to run ok as there is power and the white light flashes on the front of it. I have updated the firmware which installed correctly and even run the WD diagnostics tool and it can find it and says it is operating ok. It also shows up under the Disk Management functionality of windows. Can someone help me please as there are precious files on the drive that I do not want to lose? Thank you in anticipation of your answers.