can get the key in cylinder but can't get it to turn and open door.
any advice?

Graphite?

Paul

Never! It gums up the tumblers.

Can you get the other door open? If so, unlock the sticky one from inside & remove the handle. Dissassemble & clean & lube. You can find the How-to in my sig.

Mine used to do this. It was the latch, not the tumbler. I had to disassemble, remove, soak, and clean the latch mechanism (right behind the door handle) to free it up.