I installed Ubuntu (ubuntu-13.04-desktop-amd64) on a 8 gb pendrive. Because it worked pretty slow, I wanted to change it back to a normal pendrive. But this is what happened. Windows7 can't open the usb drive, can't view files or anything, can't access attributes. When I select to format, it says it can't format it because it is write-protected. Tried the same running from an Ubuntu, and trying from a booted GParted thing. When I view the partitions, they can't be deleted either. What should I do to get it formatted?