WD Passport shows up unallocated and write protected

I have a 500GB WD Passport. It worked great until some days ago when it stopped showing up in my Windows 7. I ran the disk management and found that it is unallocated. When I try to allocate, a write protection error comes up. Does anybody know the solution to this? I am not worried about the data on the drive so anything which might help is welcome. Thanks
Answer #1
USB drives can be write-protected by modifying the StoreageDevicePolicies Registry key and WriteProtect Registry value.
1. Start>run>regedit to open Registry Editor. and press control+F to open the find dialogue box and type “use device” or “driverdesc” to open usb mass storage device. right click on it and delete. This will set the policy value to 0. then insert your usb device. It will work fine.
2. Remember: do not delete any unknow files in the registry as this will make some programes not work as usual. Do you have any Switch for your drive? (its available for some)
Answer #2
any lock and unlock function/button on your WD case