There are a few reasons why you might be facing a locked door that you need to open. You may have locked yourself out by letting a door with a spring-loaded latch or automatic lock mechanism close behind you. Or it could be that you lost the key to your deadbolt. Or you may have even broken your key off in the lock.
There are few ways to open a lock besides using the key:
Picking or bumping the lock. The best option is if you can pick the lock, but not every lock can be picked. What determines if a lock can be picked is the structure of the key and the bottom pins in the lock. Bumping a lock can work in some cases but it’s not recommended because it may damage the lock.
Bypassing the lock. In some situations you can bypass a lock by going through the door frame or some other external means. This isn’t an option if your door is correctly installed, but many doors have not been properly installed. If your door is installed correctly then bypassing may damage your door or door frame, and even a scratch on those surfaces can be more expensive to fix than taking the last option – drilling and replacing the lock.
Drilling the lock. When the first two options don’t work or if the lock is broken, the final option is to drill through the lock. Once a lock is drilled it can no longer be used and must be replaced, but drilling will only damage the lock itself and not the door or the door frame.
All of this work should be done by a licensed and bonded professional locksmith. Amateur attempts to fix the situation will often end up making it worse or damaging your property. The methods above can be used on about 95% of the locks currently on the market.