Hard drives are not perfect devices and are always susceptible to disk failure. Although most of the data on your hard drive is probably very important to you, you may have extra sentimental attachment to your music library, making it irreplaceable. Therefore, you should back up your iTunes library so that you will not lose your music if your drive fails. iTunes provides a built-in utility to help you back up your library to a CD or DVD, but not to a memory stick. To back up your iTunes library to a memory stick, you will have to do it the old-fashioned way.
Launch iTunes and select "File," then "Preferences." If you are on a Mac, you should select "iTunes" and then "Preferences."
Select the "Advanced" tab at the top of the window. From this menu, make sure that the check box next to "Copy files to iTunes media folder when adding to library" is selected. Click "Ok" to continue.
Click "File," "Library," and "Organize Library." Select the check box next to "Consolidate files" and click "OK."
Connect the memory stick to your computer. If you computer does not have a direct memory stick input slot, you will have to use a USB memory stick card reader.
Locate the iTunes music folder on your computer. In Windows, this is located in "Documents and Settings," "Username," "My Documents," and then "My Music." On a Mac, this folder is located in "Users," "Username," and then "Music."
Copy the iTunes music folder, which contains your iTunes library, album artwork, and iTunes music. The library files tell iTunes information about how your library is organised. Right-click the folder and select "Copy."
Open your mounted memory stick. On Windows, you can find the drive mounted in "My Computer," or "Computer." On a Mac, you can find the drive mounted on your desktop.
Right-click inside of your memory stick's folder and select "Paste." The back up may take a long time if you have a large amount of data.
Eject the memory stick drive from your computer. You will now have an extra copy of your iTunes library backed up to your memory stick.
Your memory stick must have enough free space to fit your iTunes library.