If you look closely at the "L" key on your keyboard, you will probably see a small blue "3," like the image below. If this is so, then a BIOS setting to "lock your Fn key" is turned on and needs to be turned off.
As you have it set now, this "Fn lock" provides your small laptop keyboard with a full numeric keypad (similar to that on a fullsize keyboard) to make repetitive number entry easier. A laptop shouldn't default to this setting, IMO, but some may, or you may have changed it intentionally or accidentally. Some people desire this option.
Warning: Changing this BIOS setting can make it seem like your login password no longer works, if your password uses any key that has any of these alternate (blue) characters. You may have to use "Fn + key" on your password when before you only used "key" by itself. So it's a good idea to change your password (root password too, if root is enabled) to be sure of not using those keys. Then find and change the BIOS setting for Fn key locking when you are sure that it will not interfere with you logging in.
