first, lets isolate if its a windows issue. Restart the computer and when you see the IBM logo, go ahead and hit the Acces IBM button to enter the IBM Pre-Desktop. Also try hitting the F1 ket immedietely after restart, even before the IBM logo appears to enter the bios. If it works, then the keyboard is fine.
if it doesn't then I would suggest downloading their Hardware maintanance Manual and floowing instruction to remove and re-seat the keyboard. Its the simplest procedure to remove just 4 named and numbered screws clearly shown with detailed pictures of every step.
If it works outside the OS, then go to device manager and see if keyboard is present in entry.
I would suggest you go to http://forum.thinkpads.com/
for speciality support. All this assuming you do not have warrantee, else it is just a phone call to one of the best support out there.