Try booting into safe mode, and see if the function keys work there. You should be able to hold the F5 key down as windows is starting to get it into safe mode.
With nothing open, or all programs minimized, F1 should bring up the Windows help file.

In Windows XP click Start | Control Panel, then 'switch to classic view' (if necessary). Double click on the System icon, then switch to the Device Manager tab. In Windows 9x you can hold the Alt key down and double click the My Computer desktop icon.
What is listed under Keyboard? Try deleting it here and reboot to have windows reinstall the drivers (that may work better than updating them).

In the Control Panel Keyboard applet, is the correct keyboard language and layout selected?

Do you have access to a different computer, that you could try swapping keyboards with? If everything looks fine with the drivers and layout, it is possible there is something physically wrong with your keyboard. If your keyboard does not work on a different computer and that keyboard works for you, then the problem is probably the keyboard itself. If your keyboard works fine on another computer and that keyboard stops working on your computer, then the problem is with some Windows or keyboard setting, or a background program.
Your friendly neighbourhood computer store shouldn't have a problem booting a computer up with your keyboard to see if the function keys work (especially if that was where you bought it and/or it is still under warranty).



If you can not get your keyboard working, here is my keylist file. You will need to edit the file to reassign the hotkeys to non-function keys. If you are playing a mage and use certain spells, LMK and I can assign hotkeys to them (playing a warrior, many of the spells I had were from bought spell books or quest rewards).

F1 - minor restoration potion
F2 - minor healing potion (once you level up a bit, restoration potions are better)
F3 - Restoration
F4 - Freeze
F5 - Meteorstrike
F6 - Life Leech
F7 - Spellshield
F8 - Aura of Guarding
F9 - Telekinesis
F11 - Elemental Strike
F12 - Poisonous Cloud