Hello, I've recently bought a reconditioned Dell Latitude laptop, but it didn't come with any manuals. I just want to know EXACTLY what the F keys DO! e.g. what do I use F1, or F7 etc. FOR? Every so often I start to type something, and realize that somehow I must have hit some key that changes the characters I want to something else. Driving me crazy! Any help will be most gratefully received.