Helping people with computers... one answer at a time.
Your computer's BIOS, or Basic Input/Output System, is the software that initiates the computer's boot process, maintains the time while the computer is off, controls access to various hardware components, and in some cases provides a useful layer of security - all before a single byte of additional software is loaded onto the machine.
Your computer's BIOS will be set to look for boot devices in a certain order. If that is causing problems, you will need to reset your boot order.
Very often, the system will reset itself properly when you replace the battery, but there is an easy way to grab those screens to make sure you don't lose important settings.
Most computers with a CD or DVD drive can boot from that drive, but it frequently takes a small configuration change in the computer's BIOS.
A BIOS password provides a surprising amount of security on a computer. So much so that if the password is lost, the chances for recovery are slim.
Your computer will be set to boot from various locations in a certain order. To boot from a disc, you set the boot order in the BIOS.
Many computers are built with the BIOS password protected from reset... for good reason. There may be a way to still recover your data.
Your computer's BIOS can be configured to boot from any of several devices. If one looks bootable to the BIOS but isn't, you can run into problems.