Use a clothes hanger.
It depends on on what the door is. Call a locksmith first. More information would be required as different vehicles must be opened using different techniques. Clothes hangers don't always work and may cause damage.
If the door on a Hyundai Gl will not open from the inside, the child safety lock mechanism should be checked. The lock mechanism is found inside the door jab underneath a label that says 'child lock'.
If the lock switch is set to unlocked and it will not open from the inside or outside, the door lock arm may have fallen lose. Take the inside door panel off and check around the door levers and door lock.
well if you have a knife or a paper clip you can pick it
Remove the door panel, find and repair the lock linkgage.
Did you check the door latch/lock. The latch part might be broken on the inside. If you have the door already open it is easy to chisel out the old door latch inside of the door.
== == Pull on the inside door handle and it will release it so you can reset the mechanism with your fingers. This solution also worked on a Chevy Astro van 1990.
You can open a locked door (From the outside: With a key)(From the inside: With the lock opener, usually by twisting it) :-)
If the door is open. or any door is open. All doors will lock but the drivers door. I guess so you don't leave keys in. That's how it works on my 99.
I think this is a safety measure to keep you from locking your keys in the car. Try locking it with the key after the door is shut.
The child lock could be on.
Unlock it from inside the car with the door lock.
Open the keys with the door.