Hi there and welcome
As the first step, can you please remove the battery from the phone and wait 10 minutes.
Put the battery back in, turn it on and tell me please if the keypad is now working
Can you go to Settings, Applications Manager.
Then swipe to the list All and look in this list for google services framework
Press it and press clear data
Once done, restart the phone and tell me please if you are able to now use the Keyboard