Often doors are difficult to close or lock, catching at top or bottom of frame, let in drafts, in most of these cases adjustments is required to rectify these faults.
Door locks come in many types and sizes, most of the modern locks have multipoint locking, and when lock fails in most cases a full replacement is required.
Doors are normally fitted with safety glass which can get damaged due flying stones from lawn mowers or grass strimmers. These often shatter or chip glass. These broken or damaged sealed units can be replaced by removing damaged glass and fitting new glass.
These are normally activated by pushing a button or lever down then dead locking with a key. Often levers can snap or lock fail due to wear or miss use. These come in many types and in most cases can be replaced.