While this could be a hardware issue, it's always worth trying the following.
Open windows Control Panel, open Device Manager, expand Keyboards, right click the entry 'Standard PS/2 Keyboard' and select Uninstall.
Shutdown the notebook.
Unplug the AC Adapter and then remove the battery. Hold down the Power button for 30 seconds. Re-insert the battery and plug in the AC Adapter.
Tap away at the esc key as you start the notebook to launch the Start-up Menu and then select f10 to enter the bios menu. Press f9 to load the defaults ( this is sometimes f5, but the menu at the bottom will show the correct key ), use the arrow keys to select 'Yes' and hit enter. Press f10 to save the setting and again use the arrow keys to select 'Yes' and hit enter.
Note: If the keyboard doesn't work when trying to access the Start-up Menu or navigate the bios, then it's almost certainly a hardware issue.