Electrical – Light Fixture – power but no light

Yesterday I installed a new light over our dining table. At first everything seemed to work fine, but last night I turned on the light and it sparked and the light went out. I turned off the power and left trouble shooting for this morning.

Here's what I've discovered this morning –

-The breaker wasn't thrown and appears visually fine.
-The black wire may have grounded against the mounting plate – it looks like there is a small cut in the wire insulation. This probably occurred when I was shoving the wires back inside.
-After wrapping the wire in electrical tape and hooking up the light again, it's still not working – no light.
-When testing the wires coming from the ceiling (using multimeter), there is 120V between power and ground and 120V between power and neutral.
I checked the light fixture by connecting the wires to an extension cord and it works (so the light fixture or bulbs aren't the problem).
-The light switch looks fine as do all the connections.
-Using an extension cord, I tried to hook-up a desk lamp the ceiling wires and also got no light.
-As far as I can tell, this light/switch is the only outlet on the breaker.

I'm stumped. Any suggestions as to what the problem might be?

Thanks,

-Ryan