My e-machines laptop keep alarming when i turning on mylaptop and showing broadcomundi: px-2.1 v 14.0.8 and it will just be silent the alarm only when i pressed any key from my keypad.

SOURCE: Embedded numeric keypad

To toggle the embedded numberic keypad Hold down the blue Fn (function) key and press NumLk. 

SOURCE: Alarm sounds when the computer is turned on

chang youre flix and screen

SOURCE: one of the key on my laptop keypad is not working

I suspected your keyboard is already faulty. You might need to change it. Call the service hotline for the brand of your machine and tell them to replace your keyboard.

Note: If machine is under warranty no need to pay for the repairs.

SOURCE: Alarm/siren sound

Check any alarms that may be set. Lok at the system clock, and any timing applications. Check your anitvirus for schedualed times for scaning.
Good luck

SOURCE: how do i turn the

There isn't a way to "disable" any keys on a keyboard. In most cases the Fn key is in the lower corner of a keyboard and is hard to press unless intended.