Cannot get to boot menu without password

I have an Acer desktop. I got a recovery disk because I can't remember my password. The problem is that when I start through the wizard, it says please insert disk. Well, the disc is there and not reading. The instructions I received with the disk says that I need to go to the boot menu and change my settings so it will read cd/DVD and bypass drive E. I cannot figure out how to get to the boot menu. It seems that I can do nothing without a password. I've pushed F12, but that didn't work. Help!