This is often a BIOS setting issue. When you restart your computer to boot from the USB, you might need to press a specific key (often F12, ESC, F10, or F2) to access the and manually select your USB drive. If it's still not working, enter the BIOS/UEFI settings, ensure Legacy Boot or CSM is enabled, and set USB as the primary boot device.
If you possess an original Windows XP installation CD, you can easily convert it into an ISO file using free software like ImgBurn or CDBurnerXP. Essential Tools for Creating a Bootable USB This is often a BIOS setting issue
If you possess an active enterprise or developer subscription, Microsoft hosts official, untampered Windows XP SP3 ISO images within the subscriber download portal. If you possess an original Windows XP installation
While consumer ISO links are offline, Microsoft still maintains several developer-facing and corporate resources where legacy files are hosted: Microsoft hosts official