Window locks principally have two components.
The handles often have locks, but these DO NOT SECURE the window from external access. They merely prevent anyone already IN the property from opening the window.
The LOCK to secure the window may be a ‘Cockspur’ handle with a nose that engages over the frame. (Not widely used on new windows).
The more common method of locking the window is with an ‘espagnolette’, which is operated by the handle and has two or three rollers, or (more commonly now) ‘mushroom bolts’ that engage with ‘keeps’ on the frame.
The alternative is to use a separate ‘gearbox’ behind the handle. When turning the handle, the gearbox drives a pair of ‘shoot rods’ that engage into the top and bottom (or each side) of the frame probably also with two mushroom bolts.
All these types are largely replaceable although sometimes with slight modifications where designs have changed.
As always, Aftercare can examine, advise and quote on what it required to deal with any specific issue.