Changing the locks to your home should be done when you've lost your keys; even if you get them back, having them out of your possession for any time can mean that someone made a copy of them, so now your home is no longer secure. However, this is not the only time or situation that should call for a change of the locks on your home. Note when it's good to call a locksmith to either change the locks or upgrade them, and why.
When the locks are too simple and outdated
Outdated locks are often simple for thieves to pick or otherwise force open with a simple pry bar, which is why so many homes today have locks that work with computerized technology. This technology makes it more difficult for thieves to bypass them by brute force alone; even if they force open the door, this technology can still keep your home safe. For example, locks might be programmed to automatically turn on security cameras if the doors are opened without a key or the right code on a coded keypad. If you don't have such a keypad, an app on your smartphone that allows you to control the locks remotely, or security cameras you can monitor even when away from home, it may be time for an upgrade.
If friends or family have let themselves into the home without your permission
If someone has let themselves into your home without your permission, either they have a key that you did not give them or they know the vulnerable points of your home. You can change the locks without having to ask for that key back, and have a locksmith note your home's access points. This might be poor-quality locks on windows, no lock on the door that leads to your attached garage, or an older lock on the front door that is easy to manipulate. In any case, you need to have these areas secure because if friends can get into your home that easily, so can another intruder.
If there have been many break-ins in your neighborhood
If there have been break-ins in your neighborhood, your home might be the next target. Thieves usually choose homes that are easy to break into, so it's good to consider making your home a challenge for them so they move on. Upgraded locks on your doors and windows can deter those thieves so they choose another target, and your home is secure.