House wiring-white nuetral has 120v?

My friend flipped a switch and a bulb blew out. With a new bulb it still won't work. Several other lights are now out on this floor. The breaker never went off and I replaced it with a new one still no lights. I pulled the cover on the switch /outlet and there is 120 on two white neutrals tied to a lug on the switch. A black wire on the left side off the switch has 120 all the time, on the right side the 2cnd black has zero when the switch is off and 120 when in the on position. Any ideas what is wrong? The house is from 1960. My friend and electrician says the white shouldn't have 120