Describe the pattern
Does the key resist turning even when the door is open, or only when it is closed? Does the latch retract but the door remain caught? Are screws or handles visibly loose? These observations help describe the issue without taking the lock apart. Stop forcing hardware that is becoming harder to use.
Repair or replacement
A repair may be appropriate for a serviceable mechanism or a correctable fitting issue. Replacement may be needed when parts are damaged, unsuitable or unavailable. Ask what has failed, what the proposed work will address and whether the existing key can be retained. A different-looking lock is not automatically the best solution.
Older and altered doors
Rowhouses and older properties can have hardware that differs from a modern standard installation. Preserve photographs or part markings if accessible, and mention earlier door alterations. For a managed property, agree on the permitted appearance and hardware with the responsible owner before committing to replacement.
A practical handover
Test the latch, bolt and handle with the door open and closed. Verify that the door can be secured without lifting or pushing it unusually. Ask whether the symptom is fully resolved or whether door, frame or other work needs a separate professional. Keep the service record for a recurring issue.