Key / barrel sticking

Has anyone had issues with the barrel sticking? Went out to start the car this morning and the key wouldn't turn, thought it might be on the steering lock but it wasn't . Tried the so are key with no luck. After about 5 minutes it suddenly turned and the car started, problem then was I couldn't turn the think off, it was stuck again. Anyway after a few more trays I managed to turn it off. I've shot some WD40 in the barrel but doesn't seem to want to know, any ideas please.?