The most likely reason that your door won't latch is that the latching mechanism needs lubricating. Other causes..
1. It can be worn door hinges( mainly older cars) which cause latch to striker misalignment.
2. door handle to latch attachment rod bent or binding due to worn nylon sleeve.
Defective door latch or Nader Pin needs adjustment
sounds like a bad door latch mechanism.
Try spraying the latch mechanism with WD-40. Work the latch a few times and then spray it again.
Just going by the question...I would say that the latch has gotten in "the closed door position". Be sure that the door is unlocked. With your finger lift out on the latch on the end of the door and use the door handle to "open" the door latch.
how do you fix a prosthetic leg that the release screw wont go all the way down in to the socket
usually the locking latch in the door is in the closed position. try holding the handle in the open position and opening the latch manually.
the door striker needs adjusted along with possibly the latch mechanism.
The cable between the latch and the handle may be broken or needs adjustement to shorten the cable so that the latch will fully release.
Pull the inner panel and actuate the latch manually.
If the door will not close on a 1994 Ford Thunderbird unless the latch is flipped up, the latch is gummed up. Spray the latch with WD-40 or Liquid Wrench to free up the latch mechanism. A door that is out of alignment will also cause this type of problem. Check the hinge and inspect for cracks that might allow the door to droop.
If the switch is concealed in the door latch--(common problem) Spray door latch liberally with WD40 open and close door many times--then spray with silicone should solve problem If not in door latch- could be faulty light switch or wire grounding somewhere in door switch remove, replace and check wiring
Replace the door latch.