Hi James,
Who is the manufacturer of Laptop?
Are you using external keyboard?
Most of the time when you hit letters you get numbers with laptop and the workaround is to Try hit the Fn Lock key and Num Lock Key,
If your keyboard stopped working completely then you may try the steps below:
Shutdown the laptop and Remove the battery. Hold in the power button for a few seconds. This resets the motherboard. Replace the batter and startup as normal.
If non of the options work then you may with system restore asper the Link below:
http://windows.microsoft.com/en-US/windows7/products/features/system-restore
Regards,
Syed Karim