Dang... I suppose you'll need a crash course in vi. It's the only editor you are like to have
Okay, you will need to be root. That means using
and then typing in your admin or root password.
Then you will need something like
or it may be /etc/X11/XF86Config, or other... Depends on the system but maybe we'll get lucky here
once you have the XF86Config file opened, you can use the cursor keys to scroll down and find the line you need... vi is in move around mode at the moment (it's a little odd to get used to) Look for something like:
Get the cursor near the 15 and then hit the insert key. vi will now be in edit mode and you can use the keys and delete or whatever to edit the number back to 16
when finished, hit ESC (escape) to go out of edit mode.
then you can write the file back to the disk by typing
you can then quit vi with by typing
If you screw up[ at any time, just hit ESC a couple of times and type
to get out without saving and then you can start again at the top
Hope to heck this helps you