Remove CMOS battery :
The easiest way and work on most system is to remove CMOS battery. A computer will remember the time and keep the time up to date due the CMOS battery. Therefore if we take out this battery, the computer will forgets is different hardware setting including BIOS password. Put the battery back after 30 second.
Using MotherBoard Jumper :
You should know about your motherbroad band. if you don’t know about it read the manual. The jumper has been label as CLR, CLEAR, CLEAR CMOS etc by most of the manufacture. There are 3 pins in the jumper and the middle pin will be joining to either left or right pin. Now remove the jumper and join the left pin to the opposite pin. for example if the jumper join to the middle pin to the right pin, then remove it and join middle pin to the right pin. After few second again remove the jumper and join middle pin to the right pin. Restart your PC .
By Using MS DOS Command:
This method works only if you have access to the system when its turned on because this method requires MS DOS. Open Command Prompt from Programs menu and provide following commands one bye one:
debug
o 70 2E
o 71 FF
quit
NOTE: The first character in the above commands is English alphabet "o" and not the number 0.
After providing the above commands, restart your system and it should reset the CMOS Settings along with the BIOS password.
If you are curious to know how it works? then let me explain the above commands:
In this method we are using the Debug tool of MS DOS. The "o" character present at first in these commands, outputs the values to IO ports. The number 70 and 71 are port numbers which are used to access CMOS memory. By providing FF value we are telling CMOS that there is an invalid checksum and it resets the CMOS settings as well as BIOS password.
By Using Software:
There are a few software which can also reset CMOS settings or BIOS password or both within a few clicks. But as stated above you should have access to a system which is turned on and should have access to MS DOS or MS Windows:
CmosPwd
KillCMOS
