My key bored is not working

Well, Try the Keyboard on another Computer. See if it works. If not, Replace the Keyboard.

If the Keyboard does work on the other computer, Then Check the USB Ports. See if any damage occurred because of pulling a USB Device out the Wrong Way (Like Sideways).

If the USB Ports are fine and Work, Then take your Macintosh to the Genius Bar.

An eMac cannot run Mac OS 10.6.8. What Mac model do your realy have?

I agree with You. An eMac cannot have OS X 10.6.8. A normal eMac user would OS X 10.5.8 or 10.4.11.

OS X 10.6.8 requires an Intel Processor.

Is it wired or wireless?