Final answer:
The two methods of recovering a forgotten BIOS password are using a backdoor password and resetting the CMOS battery.
Step-by-step explanation:
The two common methods of recovering a forgotten BIOS password are using a backdoor password and resetting the CMOS battery. Backdoor passwords are hardcoded by the manufacturer and can be used to bypass the main password. Resetting the CMOS battery involves removing and reinserting the battery on the motherboard, which clears the BIOS settings, including the password.