Hi Angela,
I am Dave, an Independent Advisor, I will help you with this.
The actions associated to the function keys (F1 - F12) is controlled by the manufacturer of your PC because those actions are device specific.
Try pressing Fn + Esc to see if that turns off the function lock on your keyboard.
If that does not work, I think you have a Dell, boot your PC into BIOS, in the 'System Configuration' section look for a setting to toggle between function and action/media keys