This repair is definitely beyond what you can do as a non locksmith. A part of the lock has either come loose or broken completely. I can’t say for sure whether it’s worth repairing, or better off replaced without seeing the innards of the lock.
If you can, take the entire lock off the door, make sure you grab any of the little pieces still in the door, and put it all in a bag. Take it to a locksmith with your key, and ask them if it’s worth it to fix it. Either they’ll fix it for you, or set you up with a new lock set to your key.