How can I set my function key back to how it was before?

-I have an HP Pavilion dv5 laptop and the function key has decided to switch (or my sister who used it last screwed something up). I used to have to hold the function key down if I wanted to press "f1-f12" but now I have to hold it down to adjust the volume, adjust the brightness, etc, and it's really annoying to me. Any suggestions? I have already searched and tried various "solutions" to my problem, including going through the steps in BIOS with the "action mode keys" option and nothing has worked.