I have my western digital my book home edition 500

Go to this link for Western digital my book home edition. Just copy and paste.

http://support.wdc.com/product/download.asp?groupid=111&lang=en

Make sure when before you remove your unit you use the Safely Remove Hardware at the bottom of your task bar on the right. I looks like card with a green arrow on top. This is very important as you can ruin your drive if you do not do this each and every time. I had the same unit and ruined it by not doing this. Then reset your computer and let it reset everything without your external hard drive. Check your connections and plug in to 2.0 usb port. See if your computer picks up the drive. If it does do a scan on your drive, and check stability. You can download software from WD for this. Hope this helps. Let me know if I can help you with anything else.
JimmyC