To boot from USB, you need to set your USB-HDD as the first boot device. Below is a step by step guide.
Step 1: Insert iAidsoft Windows Password Recovery USB Flash Drive in your computer and restart your computer.
Step 2: Press "F2" or "Delete" to enter the BIOS setup interface when your computer is booting.
Step 3: Select "Advanced BIOS Features", then press "Enter".
Note: Your BIOS setup may be different from the screen shot above, if your "CMOS Setup Utility" does not have an "Advanced BIOS Features" category, try looking through the different categories until you find the boot device order or consult your BIOS manual on how to change the boot device order.
Step 4: Select "First Boot Device", then press "Enter".
Step 5: Select "USB-HDD" to 1st Boot Device, then press "Enter".
Note: If you could not find USB flash drive, please back to "Hard Disk" Drives to set USB flash drive as the 1st Drive instead.
Step 6: Press "F10" and "Y" followed by "ENTER" to save the new BIOS settings, and your computer will restart automatically.