go back into bios, and select "fail safe" or "default values" or similar, this will set it back to a reasonable state. Not all are set to boot from A: first like they used to be, the boot option is normally under advanced cmos/advanced bios setup, if you go to the wrong screen and cant find it, exit that screen, if VERY unsure, exit totally without saving, then try again.
If they squeeze olives to get olive oil, how do they get baby oil?