My best guess is that the toy loosened a connection inside the light fixture. You'll need to open it up and look. I'd do this with the circuit breaker turned off. Check the wire nuts inside that connect the fixture to the rest of the fan. If those are tight and it still doesn't work, it's time for a repair (or replacement) of the fixture.

Does this fixture have pull chains or such to operate the lights? Try those. Did it have a dimmer. It's possible the dimmer blew. If it is a dimmer in lieu of the light switch, it's straight forward to replace. If it's integral to the fan, you'll have to take the fan down but it's still replaceable.