A jammed lock can cause someone to miss work, be late for appointments and, in general, wreak havoc in a daily routine. There are countless reasons for jammed locks, such as extreme weather conditions, excessive rust, and keys which break and get stuck in the lock. However, most jammed locks can be fixed if you are patient, have the proper tools at your disposal and are ready to spend the time needed to fix it.
Verify that the key you are using is correct. If you live in a climate where temperatures are below freezing, the key may not work until it reaches a certain temperature. Breathe on the key and attempt to open the lock once more. Keep in mind that if you are trying to open a jammed lock in extremely hot conditions, you can put some dirt on the key, wipe it off then use a file to grind down the key.
Lubricate the lock. Use silicone thread lubricant to moisten the jammed lock, making it easier to insert the key. Consider putting a small dot of graphite in the keyhole if the lock still does not open. Once you have applied graphite to the key, try to open the jammed lock at least four times so the graphite has a chance to work.
Verify that the deadbolt is in the proper position. If the deadbolt is not properly aligned, it will need to be adjusted so it can sit in its proper place against the strike, which is located on the jamb. Consider using a file to make the strike hole wider, or take off the strike by using a Phillips head screwdriver and placing it back on the jamb in its proper position.
Remove the entire plate which covers the lock. Retighten the screws then attempt to open the lock again. Keep in mind that the lock will need to be replaced if it is still not working at this point. Purchase a new lock at a hardware store in your area, and install it on your own or have a professional assist you with the installation.