In this video, I will show you how I started my computer from a USB flash drive which had Ubuntu 10.04 LTS insyalled on it. The computer I am using is an HP a1720n desktop computer.
First, I press the pause key right after I turned on my computer to pause the start up process, and then I press the F10 BIOS entry key which may be differrent for your computer. I use the arrow and enter keys to navigate to the boot menu. I made sure hard drive was the first device to boot and my flash drive in the hard drive group was on top by using the – or + numpad key to bring the drive up or down, so my flash drive is on the top of the hard drive boot order group. Lastly, I press F10 to save and Exit my BIOS session. I wated for my computer to boot into Ubuntu from my flash drive. I then click the “try Ubuntu 10.04 LTS button” and waited for my PC to load Ubuntu in Live USB flash drive mode.
If you want to shutdown your computer after use, click the power button on the top right of the desktop and pick shutdown. When your computer shut down remove your flash drive from your USB port.
The next time your computer starts up it should load the operating system from your first hard drive on your computer unless you still have the USB drive plugged into a USB port.