What do you mean it won't boot? Without pressing anything at the POST screen, what happens next?
After the POST completes, it will attempt to find a bootable device attached (hard drive, CD/DVD drive, floppy, USB). If it fails to find bootable media, it will generate an error message.
If it won't see the recovery media when you boot, you may need to change the boot order in the BIOS settings or press F12 for the boot menu and select the device you want to boot from.
