how can i fix my usb memory stick?

Get a LiveCD Linux - (eg. Ubuntu) - Run it - it's an installation without touching your hard-drive. It's absolutely an installation of a Operating System as Windows. It may take some 3-6 minutes, depending on the computer. Plug your stick. Place the information somewhere on your computer. Shut down your LINUX and restart normally in Windows your computer. Done.
Better with LINUX you might see passwd protected partitions on other computers; Microsoft should also be a free software, because it's not worth completely the money.

Vlad
May 2009