|Try looking in the user manual for your model. There may be a way of setting something so the Fn key is off by default rather than on, or visa versa. |
If this an an older much used laptop, your problem may be because of a sticking key or keys, and usually the only way to fix that is to get a replacement keyboard module.
Most laptops that have a single PS/2 port have one that is wired such that either a PS/2 mouse or a PS/2 keyboard can be connected to it.
You can make do with a regular keyboard plugged into your PS/2 port, if you have one, to do most things. If you are using a PS/2 connected mouse, you can get a standard Y cord wiring adapter you can connect to the single PS/2 port and use both the mouse and the keyboard.