You will have to take off the inner door panel and check the mechanism inside, a piece of the latch might have broken off.

Have fixed our PT Cruiser driver door inside latch several times. inless than 5 minutes.
It is a plastic coupling that has come disengaged and can be inserted back in place into the metal door pull. There are 2 bolts to take out through the underside of the armrest, and 1 screw out of the latch mechanism housing. Once off, it's a matter of "popping" the door panel off. Use a plastic bag to protect your paint and slip a putty knife under the panel at the bottom. Pry it away from the metal enough to get your hand under the panel and give it a tug until the plastic 'snaps' start popping out. Careful so as not to break them. They snap back in to hold the door panel. Also, the remote mirror cover in the corner of the window just snaps in and out - grab it with your fingers and pull. The cables to the mirror should remain intact, but you will need to move it just enough to get it out of the way. There is a rubber channel and seal at the window bottom that you will do better just to pull it out. It rides on the lip of the sheet metal and goes easily back into place. The top lip of the door panel rides in the channel. Once the panel is away, it will still be connected by the lock "button" (which slips in and out) and wiring to the automatic lock button. So careful not to bend the manual lock button cable or pull any wiring loose from the lock switch. The plastic piece is easily clipped back into the door latch. it may not appear to be worn or broken, and it is still a mystery to me why it pops out. I think my wife is too agressive with her door opening. It only happens to her.