The last time I called a locksmith to fix my front door lock, it ended up being $300 for him to install a whole new lock. He mentioned that a part commonly breaks on the inside but he could only sell me a new handle.
That experience felt exploitative and caused me to procrastinate hiring a pro to fix my new problem, despite not being able easily open the door from the outside, for a very long time. It was a daily irritant but I hated the idea of calling a locksmith again. Finally, the other day, the difficulty opening the door finally became too much for me so I thought I'd attempt a DIY repair first.
I am SO happy to report that the internet made it possible for me to replace the broken part myself for less than $10 and a couple hours of my time. I found a short video with a step by step diagnosis and fix. Then the internet showed me replacement parts "near me." With a part nearby, I had the courage to take the handle off and try to fix it. I took the old deadlatch with me to get the new one and make sure it was exactly right. Once home, I easily re-installed the handle. Woo hoo!
The red colouring below shows where the catch that retracts the latch has worn away. Therefore, the part of the outside button that is supposed to strike and move the catch doesn't move it far enough anymore to retract the latch fully.