My Passport 500gb doesn't work on Windows 7

Data get corrupted when you write data to drive via a bad USB connection. Most of the time you can correct these errors with HDD Regenerator 2011. But you need to use good USB connection. Read section related to HDD Regenerator 2011 on this post.

http://community.wdc.com/t5/My-Passport-for-PC/How-to-eliminate-potential-problems-on-USB-Powered-Drives-and/td-p/118262