To troubleshoot why your computer is not booting from a CD or USB drive, please do the following:

1. Ensure that the USB drive or CD drive is bootable, such as a Windows installation disk
2. Check the boot order within the BIOS setup
3. Verify that all the connections to the CD or USB drive are properly connected
4. Check the system for any unusual beeps or lights that might indicate a malfunction
5. Ensure the USB drive or CD-ROM drive is working properly by testing it on another system