RE: Ignition key won't work in door
Common, common, common!
Your first sentence answers your question.
If the tumblers are not used for a long time, they seize solid. If you're lucky, you might be able to free them up by forcing WD-40 into them with the red tube and letting them soak. If not, they must be replaced.
We advise all our customers to use the door tumblers at least once a week. We also squirt graphite based lube into them when we do the "lubricate all latches, hinges and mechanisms" portion of scheduled maintenances.
On a fairly regular basis, we see this scenario:
New customer comes in, leaves his vehicle and key but takes his remote.
Car jockey locks vehicle after parking it on service lot.
Technician goes to get it...
Service advisor phones customer: "Sir, we're sending a car jockey to your office to get your remote. We can't get into your vehicle. Or if you prefer, we'll have to SlimJim our way in."
If your trunk tumbler hasn't seized yet, it will soon without some preventative maintenance!