Hard disk problems are quite common these days, and when they fail you have no other option but to replace it. Fortunately, Ubuntu has been designed to run on your USB stick!
Most laptops are enabled to boot from a USB device, and you can create a persistent USB flash drive so that programs and settings are saved during shutdown.
Step 1 Get Ubuntu
Download the newest version of Ubuntu and burn onto a blank disk.
Step 2 Boot from the CD
Insert the Ubuntu CD into your PC and boot from it (change your boot up settings).
Step 3 Plug Flash Drive In
Insert your Fat 32 formatted USB flash drive (at least 4GB is recommended).
Step 4 Go to Startup Disk Creator
Found in System > Administration > Startup Disk Creator.
Step 5 Choose Ubuntu as Source
Choose your Ubuntu .ISO image file as the source. The .ISO must be saved on your internal hard drive.
Step 6 Choose the Flash Drive for Startup Disk
Choose your flash disk drive and be sure to click "Stored in reserved extra space" to make it persistent, otherwise you won't be able to save recently installed programs or stored documents. You can reserve up to 4GB on a larger USB stick.
Step 7 Make the Disk
Now just click on "Make Startup Disk" to install Ubuntu onto the flash drive.
Step 8 Boot with the USB Stick
After the installation is complete, remove your CD and shutdown. Then, boot using your USB device.