If it's out of warranty, repair won't be free.
Select a repair shop that can do it quickly, or that can provide you with a laptop to use for how long it takes to repair.

But first I would try:
1. Does the keyboard work enough to get you in the BIOS (press the magic key) and does it work there?
2. Can you boot from a Linux disk and does it work then?
If both are yes, it might be a driver or setting issue in Windows. Then go back to factory conditions the way the user manual tells you or from the recovery disks you made (you did make them, didn't you?)

Kees