Many, if not most, people have experienced being locked out of the house or car at one time or another. It's easy to walk out of the house or car and think you have your keys in hand when you're actually holding something else, and then inadvertently lock a door behind you; you might also misplace your keys or have them stolen while out for the evening. Whatever the reason for a lockout, note a few reasons why you always want to call a locksmith to get you back into your house or car, rather than trying to break in, pick the lock, or otherwise manage the situation on your own.
Keys are easy to break
It's never good to try to force a lock open by using a similar house key, or someone else's car key even if they have the same type of car as you. Each key is shaped and formed to fit different locks in particular, and jamming them into a lock and trying to force that lock to work can cause that key to break very easily.
If a key is jammed into a lock so severely that it breaks, this can also break the pins and tumblers and other parts of the lock. Once this happens, the lock may need to be outright replaced, which is usually a more expensive service than having it opened by a locksmith! You would also have the expense of replacing the key that was broken. To avoid this, have a locksmith open the lock rather than assuming that a key you can fit into the lock might suffice in forcing the lock open.
The lock may be salvageable
Even if a lock seems outright broken already, or there is something jammed inside the lock itself, that lock may still be salvageable. A locksmith may be able to quickly pop the lock out of the door, open it up and repair whatever is broken inside, or remove any debris, and then put the lock back into position.
Trying to pick a broken lock or trying to remove debris inside the lock yourself, even with a bobby pin or paperclip or other small tool, can mean causing even more damage to the locking mechanisms. You might also wedge that debris that's in the lock even further inside, actually ruining the lock itself.
For more information or advice, contact a lockout service.