Mismapped keyboard keys? How to correct them by software means Now I had a problem with my keyboard. 

When I press shift and number keys, 
the output is different than expected. 

When I press Shift plus 2, it gives me "

when I press Shift plus ;, it gives me +. 

when I press [, it gives me @.

All the symbols are strangely mapped. I thought something was wrong in the keyboard routing or processor. I checked system preference -> keyboard:

Here is what I see;



So strange! Apple recognizes the wrong mapping but continues it! I want it back to normal mapping.. Is there any way to do it or actually create a software mapping so that SHIFT PLUS 2 is @ ?

Thanks 
Indeed this layout belongs to a Japanese Layout, obtained from http://support.apple.com/kb/HT2841:  Now the question is how to remap it back to a US layout..
Your mac for some reason thinks you are using a Japanese JIS hardware keyboard instead of the US ANSI or European ISO. Notice the Yen key at top right. What kind of keyboard do you actually have?  This note may help:

http://m10lmac.blogspot.com/2009/12/fixing-keyboard-type-problems.html