Unfortunately, when this type of error occurs, it means that the USB
drive is failing. :( It's a great job what you did with the Command prompt, but there are a couple of troubleshooting that we could try, shall we? :)
Firstly, I would extract the data through third-party software like a data recovery program, then, if that doesn't help, I would go for the Linux
Live CD. This OS could help you to see the files as it reads in a different way than the Windows does. You can find the step how to make a bootable flash drive on the Ubuntu forum
, but beware to only try it later, not install it, when you boot form the USB drive your PC.
Hope that I gave you some ideas.