Start by trying to push the lock button.
Thumb press door handle sticking.
Once you let go of the knob grab the end of the latch bolt with your fingers and pull.
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.
The most common cause of sticking door handles is some kind of malfunction within the tubular latch itself.
Open the door and squirt graphite powder into the key lock.
Turn the handle of the doorknob to expose the bolt.
If the latch bolt doesn t move and is fully extended the issue is with the strike plate.
Remove the cap on the graphite powder.
Squirt the bolt with graphite powder.
Push and hold the button in.
If the latch bolt moves it is sticking in the door knob and requires some disassembly to fix.
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.