Hello @Dan3
Thanks for sharing your question about your door handle. It's likely that that there has been a mechanical failure somewhere in the door latch. I propose two possible solutions, first is to replace the door latch. There are generic ikonic latches that might be compatible.
I suggest taking your door handle apart and removing the door latch itself. Bring it to your local store and compare it to the generic sets available and make sure that they are identical. The second solution is to replace the entire door handle set with a new one.
Here is a handy step-by-step guide: How to change a door knob
If you have any other questions we can help with, please let us know.
Eric
