There is another way to change the Fn Key behavior in Inspiron N4110. Follow the steps below to change the Fn Key behavior:
1. Power on/Restart the computer.
2. Start tapping the F2 key when the Dell Logo appears.
3. Enter the System Setup (BIOS).
4. Go to Advanced tab by pressing the right/left arrow key.
5. Using the down/up arrow keys select Function Key Behavior and hit Enter.
6. Choose Function Key and hit Enter.
Please revert for clarification.