Cannot turn key to unlock the door

SOURCE: 2000 Grand Am SE 4-Door

This is only a possible solution to your problem. I had similar problem with my car. It turned out that the window locking toggle on the driver door not only prevented the other windows from being opened by passengers but also controlled the door locks. When I unlocked the window control I was able to unlock the door. Another possibility is the armature inside the door has come off the locking mechanism.

SOURCE: key turns in manual door lock but doesn't unlock truck door

you need to remove the door panel....the linkage for the lock has come disconnected...it shouldnt be too hard to reconnect

SOURCE: 90 525i bmw key will n ot lock/unlock door and door will not clos

I would check the door lock actuator and the actual linkage. you need to remove the outside handle assembly for full inspection. on your model year car the linkages sometime wear out at a camon the handle that rotates the linkage. sounds really like you have worn linkage/handle.

SOURCE: key lock on drivers door won't unlock the door

you need to take the door panel off, there is a rod in there that connects to the lock cylinder it frequently pops off, there is a little plastic clip that should hold it on to the cylinder it may be broken!!

SOURCE: Unlocking the passenger side door of my TOYOTA

Its normal. Mine is the same way, I was told by Toyota service dept if you unlock the door for a passenger you will then go to the drivers door to get in, If youre unlocking the drivers door, then you will unlock the passenger door from the inside if you want, thus preventing someone from jumping into the passenger side and carjacking you as you get in.