If your vehicle is showing door won't open from the outside, here are the most likely causes and the parts you'll need to fix each one.
The internal plastic or metal pivot points of the exterior handle have snapped. Pulling the handle no longer engages the release rod inside the door.
The metal rod connecting the exterior handle to the door latch has popped out of its retaining clip. This is highly common after recent work inside the door, such as replacing a window motor or speaker.
The latch mechanism inside the door has become rusted, gummed up with dirt, or suffered an internal spring failure, preventing the outside handle's input from releasing the door.
The electronic actuator is physically stuck in the locked position. Even if the unlock button is pressed, the mechanism fails to engage the outside handle's linkage.
In freezing temperatures, moisture inside the door latch can freeze solid, preventing the mechanical parts from moving when the outside handle is pulled.