There are many types of deadbolts, but these tips work on most. First, address any grime buildup. A bit of WD-40 will loose up rust and dirt so the deadbolt can turn. Inspect the door and frame alignment if this doesn't resolve the issue. Adjust the strike plate or the deadbolt's position to improve alignment. If the problem persists, disassemble the lock to inspect for damaged or worn parts. If you are unsure how to do it, hire a local locksmith.

Begin by checking the power source, typically a battery or wired connection. Ensure the battery is installed correctly, has sufficient charge, and isn't corroded. If it's a wired lock, examine the electrical connections to confirm they are secure and free from damage. Additionally, inspect the lock's programming or settings. Confirm that user codes or access credentials are programmed correctly and that any remote control devices are paired and functional.

Expect to pay between $50 to $200 if you hire a locksmith to change your locks. That figure includes labor and the cost of basic hardware. The cost will naturally be higher if you plan to install more expensive locks, like smart locks, and if you need a lot of them.

Homeowners can save money by replacing locks themselves. A typical rekeying kit costs about $10 to $25. The only additional cost is purchasing new house keys, and those are no more than a few dollars per key. If you want to replace the locks on your own completely, the main cost is the price of the locks themselves. A standard knob-style lock starts around $25, while electronic locks and smart locks will run in the hundreds of dollars. The only additional tools you should need are a tape measure, screwdriver, and screws if they are not already provided.

If part of the key is protruding out of the lock, you can use a pair of needle-nosed pliers or tweezers to gently turn the key in the lock to open the door. If the key is fully inserted into the lock, you may also be able to use a key extractor to help turn the key into the unlocked position. 

But if the key breaks off halfway into the lock or you simply can’t reach it to help engage the unlocking mechanisms, you should probably call a professional.