Try a tube of graphite in the key hole. One puff of power will lube the pins inside the lock. Don’t over do. Squeeze the tube once and that’s all you need.
If that doesn’t work, you may have a small burr on your key. Try vigorously rubbing the sawtooth edge of the key agains another key edge, as if you were trying to cut the other key in half. It’s not enough to damage either key, but may dislodge something you’re not seeing.
Is it a Schlage? (Sp?) If so, if it was mounted ‘upside down,’ there’s a good chance the pins have all dropped out of alignment. This happened to me last month, about two weeks after the lock was installed. Cost me $65.00 and the locksmith told me the condition I describe was becoming common with that brand.
I have Kwikset locks that I inherited with the house. One of the deadbolts can’t be opened with a key. When you try it, the entire core comes out. Even the locksmith couldn’t fix it when he re-keyed the place. POS.
He could not? did he offer to sell you a replacement?
I cannot for the life of me understand how it could not be repaired. If the plug is coming out then it is a clip issue, if the whole plug comes out, then the spring tabs can be replaced. very odd.
Back to lurking
No offer of a new one. He even called another locksmith who was more familiar with Kwikset, who said it couldn’t be fixed. Weird. I used to install and defeat locks as part of a job I once had, and never heard of a lock that couldn’t be repaired unless it was trashed somehow.
FYI, some locks are offset to the latching mechanism and it is possible to install either key side or latch side upside down which would cause them to bind.