UNetbootin allows you to create bootable Live USB drives for Ubuntu, Fedora, and other Linux distributions without burning a CD. It runs on Windows, Linux, and Mac OS X. You can either let UNetbootin download one of the many distributions supported out-of-the-box for you, or supply your own Linux .iso file if you've already downloaded one or your preferred distribution isn't on the list.
Requirements
Microsoft Windows 2000/XP/Vista/7, or Linux, or Mac OS X 10.5+. Note that resulting USB drives are bootable only on PCs (not on Macs).
Internet access for downloading a distro to install, or a pre-downloaded ISO file
In case your hard drive is damaged or corrupted then it is better to have functional copy of the drive where you can store your stuff immediately. Cloning a drive is a good option for handling such situations. Have a look on this tutorial.