1
Please provide more information on the functions on your laptop/tablet you are now unable to use, is that the function keys (F1 - F12) on your keyboard or is it something else?
2
If the problem is the function keys, the actions associated to those keys are not controlled by Windows, because the actions vary from laptop to laptop, the actions are always controlled by the laptop manufacturer.
If pressing a function key does not produce the correct action, try pressing Fn + a function key to test if that works, if it does, press Fn + Esc to disable the function lock on the keyboard.
If that does not resolve the problem, boot your laptop into BIOS and look for a setting to toggle between the Function Keys and Action/Media keys.