Lost BIOS Password

I owned a laptop that is an Acer apire 4720. A month ago i was assigned to a field work. I got scared with the current environment and think of the possibility that someone might stole my laptop. i go to BIOS setting right away and put a password on the bios. It turns out fine until i got back to the office and when i tried to boot a windows CD. it doesnt work so i go back to the bios again and it ask me for the password. I tried to enter a password 3 times and it's locking automatically. I tried some of the passwords i normally use and still it does'nt work. Anyone can help me to fix the problem!