The most common cause of sticking door handles is some kind of malfunction within the tubular latch itself.
Thumb press door handle sticking.
Remove the cap on the graphite powder.
Push and hold the button in.
Turn the handle of the doorknob to expose the bolt.
A door knob lock button stuck has a few quick fixes that you can try out.
Turn the knob to open the door and release the knob slowly.
Release the button quickly try sliding your finger off the button so the pressure is maintained up until the precise moment of release with no backing off.
Open the door and squirt graphite powder into the key lock.
If the latch bolt doesn t move and is fully extended the issue is with the strike plate.
To test this firstly open the door and check that there are no obvious obstructions on the tubular latch plate such as loose screws or signs of internal parts of the latch or lock poking through.
Start by trying to push the lock button.
The issue a door latch stuck due to a jamming latch will have no real variation between how the latch moves when it is pressed in or when the handle is turned both when the door is open and when it is shut.
If the latch bolt moves it is sticking in the door knob and requires some disassembly to fix.