Letters and numbers on Mac will not respond

Somebody please help me with this before i throw my power mac off the house.

I have a G5 Power mac running OS X, I have just bought a new aluminum USB Mac keyboard to replace the one that came with it before I thought it was broken. However, when I plug up the brand new one it does not work either.

Innitially only a few keys on the older keyboard wouldnt work, so I read online and it told me to go into the system files and delete some associated with the keyboard, than reestart and it would recreate them and it should work.. but by the time I got done doing that none of the letters or numbers responded.. So i bought a new keyboard and the same issue occurs. I am considering just formatting the OS but I am hoping somebody can give me a different solution.

I also have tried creating a new user and deleting the old one, with no luck.. somebody has got to know whats going on here.