There is no separate switch for the light. It operates through the logic board.

You could carefully check the socket with a meter and make sure that you get 120V through the contacts.

If you do, make sure the contact at the bottom of the socket will touch the bulb when it's screwed in. Sometimes they get "flattened" and need to be pulled up a little.

If you don't get power the it's time to look at the board and see what's failed.