I was once called to a man's home because his hall light stopped working. When I got there, I promptly found the breaker panel. Breaker was on.
Took the cover off, check with the tester, breaker worked.
Went to the switch, took the cover off, tested the switch. Worked fine, had power in and out.
Took down the light, checked the connections. All fine.
Asked if they tried changing the bulb. They did.
I reinstalled the light. Went to put the bulb back in, noticed it had a broken filament.
To keep from disrespecting the homeowner, I told them I broke it, and asked for another. They had two more left in the box.
I grabbed one, broken filament. Grabbed the last one, broken filament.
Stole a bulb from a working lamp and, ends up, light worked fine. The box of bulbs was bad.
You know where I'm going with this -
Did you try another box of bullets?
Not to be a wiseguy, but worse has happened, that's for sure.