Copy and Paste Keyboard Shortcut not working

If you have your Keyboard Viewer turned on so you can see the effect of using
the keys as you type them, you may be able to tell if the keyboard is defective.

A spare keyboard and mouse are among important extras to have on hand.
Especially if you happen to live in a location where replacements don't exist.

Is there something stuck under one of the keys, and stopping their function?
You may be able to remove a key-cap to clean the area; and hope it works.

Not sure what kind of 'reset' may help a keyboard see only a few keys that do
not appear to be functioning; however you may be able to determine if that
keyboard is defective or not, in a matter of trial & error by trying the Keyboard
Viewer. If you do not have it set up on the menu bar for easy access, you can
set it up by going to System Preferences > International > Input Menu, and be
sure your preferences are selected; and choose to have Input menu appear
on the top right side of the desktop by the clock.

There is a way to use a Win/PC keyboard in place of a Mac keyboard, but there
are some keys that are incorrect or in the wrong places; so remapping them is
one of the ways to still use a Mac if you happen to be without an Apple keyboard.
(Some Mac users running Windows via BootCamp have both keyboards.)

Anyway, I'm not sure if some system problem may be the cause of the keyboard
not working correctly; or if the keyboard has some defective keys acting up. Some
of the system resets probably will have no effect on the keyboard input to a Mac.

Resetting PRAM/NVRAM? Reset PMU/SMC, etc? SafeBoot & repair permissions?
These are unlikely; out of desperation, something may scare the gremlins out of it.
But nothing will reset wear and age if the computer's keyboard is wearing out.

Perhaps someone else will have ideas to get around this issue; short of an attempt
to set different keys on the keyboard to perform the missing functions of others...
In lieu of a known-good USB keyboard to try instead of the one you have now.

Good luck & happy computing! 🙂

The 'input menu' would put a small flag on the main menu bar and allow
you to click there, and see Keyboard Viewer, and Character Palette. A
small keyboard will appear on the desktop and mirror all keys you use
on the real keyboard. Or not. When they don't work in the Viewer, you
can safely assume they don't work. (Or it is software, vs hardware.)

Someday, when you have time and perhaps some extra hardware, you
may consider making a backup clone of your computer contents on a
large enough external hard disk drive to support bootable OS X clones;
and also large enough to have more than one partition there, for extras.

Then, do a completely new installation on a 'secure erased' hard disk drive.
And then update it. You could migrate previous user setting info, into the
new installation from an external drive's clone; or if you have extra discover
time, you may find a cure to the underlying problem's cause and use the
clone in the external hard disk drive as a backup. Maybe DiskWarrior?

The problem in the system may be due to at least one possible malady; a
corruption of system data, a bad block on the hard disk drive, or some other
matter that somehow became bigger than life when combined with another.

You may try the SafeBoot mode, repair disk permisions in Disk Utility, and
then try reinstalling the Mac OS X 10.5.8 Combo update file, on top of it all.
Then when it restarts, run SafeBoot again and re-repair disk permissions.
(But any actual hard disk drive issue may exist and remain unattended.)

Odd problems often are best attacked at a root level, after you have adequate
backup; a bootable clone on supported self-powered external hard disk drive.
Clone utilities such as SuperDuper and Carbon Copy Cloner are fine tools;
and CCC (bombich software) has evolved to be top-notch with site support.

Glad you were able to remap some keys; I found several links in a search on
how to do that, and had previously posted some URLs to help someone else
on another user forum that covered some angles of resolving keyboard issues.

Good luck & happy computing! 🙂