If the window reaches the closed position but the latch will not engage, the problem is often alignment between the lock and keeper, loose screws, debris, or a sash that no longer sits in its original position. Do not use the latch to pull a window that requires heavy force; that can break the hardware without fixing the cause.
Close the window by hand and compare alignment
See whether the hook or cam sits above, below, or sideways from the keeper. A small mismatch points toward hardware adjustment rather than replacing the whole latch.
Tighten loose screws before moving parts
A shifted keeper may return to position when properly secured. If a screw spins without gripping, repair the attachment rather than tightening harder.
Do not compensate indefinitely for a sagging sash by moving the latch
If the window rubs or leaves gaps, the main issue is alignment, hinges, or rollers. Moving the keeper too far may make the latch engage while leaving a poor seal.
A broken latch needs a compatible replacement
Do not improvise with screws that block an emergency exit or alter an egress window. Use system-compatible hardware and preserve required opening functions.