Wired keyboard issues-caps lock won't turn off and other keys do not type

Question

I sat down today to use my May, 2010 iMac.  Fully up to date with Lion.
I am using a WIRED keyboard. 
The caps lock key is permanently on and the remaining keys when pressed do nothing.  They do not work.  You can press the keys down but they don't type any letters or symbols of any kind.
I cannot log in because I can't type my password as the keys don't work.
I can't do a PRAM reset because the  P and R keys and others don't work.
I don't know what an SMC reset is but I can't do that either because the keys don't work.
Why would a keyboard stop functioning?  Yesterday, it was just fine.  Now it doesn't work. 
What causes the caps lock key to stay on?
I have unplugged the keyboard etc, but nothing changed. 
Doesn't anyone know how to correct this problem?  Do I just need to buy a new keyboard? 
I called Apple but they were closed. 

Answer 1

Please read teh directions for an SMC reset:
SMC RESET
Shut down the computer.
Unplug the computer's power cord and all peripherals.
Press and hold the power button for 5 seconds.
Release the power button.
Attach the computers power cable.
Press the power button to turn on the computer.
PRAM RESET
Shut down the computer.
Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
Turn on the computer.
Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
Hold the keys down until the computer restarts and you hear the startup sound for the second time.
Release the keys.