Generally, there are two options to make your computer boot from CD or USB drive. When you power on your computer, check the boot-screen for setup key or boot menu key.

Option 1: By pressing the boot menu key, the screen will show a list of devices that your computer can boot from. Just use the arrow key to select your desired device (CD, USB or Hard Drive) and then press Enter. Your computer will directly boot from a specific device. This is the simplest way to set your computer to boot from CD/USB drive without changing computer BIOS settings. But the boot menu key is not available on some computers, then you need to turn to Option 2 instead.

Option 2: By pressing the setup key, it will bring up the BIOS Setup Utility. Once in the BIOS, navigate to the option that controls the boot order (this may be under “Boot” or “System Configuration” or “Storage”). There should be a list for “Boot Priority”. Place the CD/DVD or USB drive at the top of this list. Save your changes. Now restart the computer, it will try to boot from CD/DVD or USB drive before hard drive.

Usually, when you turn on your PC, there is a very short period, when the BIOS entrance command appears on the screen, but if you miss the moment, you will have to start all over again. If you know, what the keys combination you should use is, you need to press it immediately upon computer reboot, and sometimes you need to try pressing the key repeatedly as soon as the computer starts up.

The BIOS setup keys and boot menu keys are different as per computer manufacturer and even as per computer model. For you convenience, I am listing the BIOS setup keys and boot menu keys for the most popular computer models.

 
For Windows 10 or 8 computers, there are also another two ways to access the BIOS(UEFI) Setup:
2 Options to Access UEFI BIOS Setup in Windows 8 / 10

Looking to change the boot order for your Windows XP or Vista machine? By changing the boot order, you can force your computer to boot from a CD/DVD drive, a USB flash drive, or even off the network.

Changing the boot order on a PC is mostly done in order to boot from a recovery disk or from an OEM disk to run some kind of Windows repair software, such as Windows password reset utility.

So here are the steps to change the boot sequence for a PC:

Step 1: The first thing you have to do is restart your computer and enter the BIOS. You can enter the BIOS when you see a message such as Press FX to enter setup or something similar.

On a Dell machine it’s usually F2, Toshiba is F1 or ESC, HP is F1 or F2, and IBMs usually require you to go to Start, Programs and then Thinkpad CFG to start up in the BIOS.

Step 2: Now that you are in the BIOS, the tough part is finding the boot order section. Note that there are not a ton of options in a BIOS, so just go through every page if you have to until you see something like First Boot Device, Boot Order, Boot Management, Boot Sequence, etc.

It may also be under Advanced BIOS Features or Advanced Boot Options. In the above screenshot, it’s under Advanced BIOS Features. Use the arrow keys to navigate.

As you can see, there is a First, Second and Third Boot Device. Scroll down and use the arrow keys to change the device to HDD (hard drive), Removable Device (USB flash drive), CDROM, or Network. You could also have a BIOS that looks like this:

The instructions for changing the boot order are in the sidebar, but usually it requires pressing the + or – buttons to move items up and down in the order list. The first item in the list is what will be scanned first when booting. If boot media is not found, it will try the second device and so on.

Finally, go to Exit and make sure you choose Yes to the Save configuration changes and exit now? question.

That’s pretty much it! If you have any questions or can’t get into the BIOS on your computer, post a comment here and I will try to help! Enjoy!