Easily Create Bootable Ubuntu 12.04 USB Flash Drive, is very easy using UNetbootin. It will even download Ubuntu for you!
Note: Ubuntu will take up approximately 700 MB on your flash drive, so choose a flash drive with at least 1 GB of free space, formatted as FAT32.
Place Ubuntu on your flash drive
1. UNetbootin doesn’t require installation; just download the application and run it.
2. Select Ubuntu from the Distribution drop-down box, then 12.04_Live from the Version drop-down box. If you have a 64-bit machine, then select 12.04_Live_x64 for the Version.
3. At the bottom of the screen, select the drive letter that corresponds to the USB drive where you want to put Ubuntu on. If you select USB Drive in the Type drop-down box, the only drive letters available will be USB flash drives.
4. Click OK and UNetbootin will start doing its thing. First it will download the Ubuntu Live CD.
5. Then, it will copy the files from the Ubuntu Live CD to your flash drive.
6. The amount of time it takes will vary depending on your Internet speed, an when it’s done, click on Exit.
7. You’re now ready to boot your computer into Ubuntu 12.04!
Set your computer to boot off of the flash drive.
You’ll need to Go into the BIOS to accomplish this.
Here is a video tutorial that might help.In this tutorial I selected the CD ROM to be the first boot device so instead of the CD ROM select the Flash drive to be the first boot device.
Booting into Ubuntu
1. If you set the right boot option, then you should be greeted with the UNetbootin screen.
2. Press enter to start Ubuntu with the default options, or wait for few seconds for this to happen automatically.
3. Ubuntu will start loading.
4. It should go straight to the desktop with no need for a username or password.
Note: The Ubuntu Live CD isn’t just useful for trying out Ubuntu before you install it, you can also use it to maintain and repair your Windows PC. Even if you have no intention of installing Linux, every Windows user should have a bootable Ubuntu USB drive on hand in case something goes wrong in Windows.